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Bortolini M, Winkler PA, Moreno JCD, Sato MT, Guareschi BLV, Petersen-Jones SM, Montiani-Ferreira F. Preliminary characterization of a novel form of progressive retinal atrophy in the German Spitz dog associated with a frameshift mutation in GUCY2D. Vet Ophthalmol 2023; 26:532-547. [PMID: 36872573 DOI: 10.1111/vop.13079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 03/07/2023]
Abstract
OBJECTIVE To describe the clinical, preliminary electroretinographic and optical coherence tomography features of a newly identified form of progressive retinal atrophy (PRA) in German Spitzes, and identify the causal gene mutation. ANIMALS Thirty-three client-owned German Spitz dogs were included. PROCEDURES All animals underwent a full ophthalmic examination, including vision testing. In addition, fundus photography, ERG, and OCT were performed. A DNA-marker-based association analysis was performed to screen potential candidate genes and the whole genomes of four animals were sequenced. RESULTS Initial fundus changes were pale papilla and mild vascular attenuation. Oscillatory nystagmus was noted in 14 of 16 clinically affected puppies. Vision was impaired under both scotopic and photopic conditions. Rod-mediated ERGs were unrecordable in all affected dogs tested, reduced cone-mediated responses were present in one animal at 3 months of age and unrecordable in the other affected animals tested. Multiple small retinal bullae were observed in three clinically affected animals (two with confirmed genetic diagnosis). OCT showed that despite loss of function, retinal structure was initially well-preserved, although a slight retinal thinning developed in older animals with the ventral retina being more severely affected. Pedigree analysis supported an autosomal recessive inheritance. A mutation was identified in GUCY2D, which segregated with the disease (NM_001003207.1:c.1598_1599insT; p.(Ser534GlufsTer20)). Human subjects with GUCY2D mutations typically show an initial disconnect between loss of function and loss of structure, a feature recapitulated in the affected dogs in this study. CONCLUSION We identified early-onset PRA in the German Spitz associated with a frameshift mutation in GUCY2D.
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Affiliation(s)
- Mariza Bortolini
- Department of Veterinary Medicine, Federal University of Paraná, Curitiba, Puerto Rico, Brazil
| | - Paige A Winkler
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | | | - Mario Teruo Sato
- Department of Ophthalmology, Federal University of Paraná, Curitiba, Paraná, USA
| | | | - Simon M Petersen-Jones
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
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2
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Saito M, Otsu W, Miyadera K, Nishimura Y. Recent advances in the understanding of cilia mechanisms and their applications as therapeutic targets. Front Mol Biosci 2023; 10:1232188. [PMID: 37780208 PMCID: PMC10538646 DOI: 10.3389/fmolb.2023.1232188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/24/2023] [Indexed: 10/03/2023] Open
Abstract
The primary cilium is a single immotile microtubule-based organelle that protrudes into the extracellular space. Malformations and dysfunctions of the cilia have been associated with various forms of syndromic and non-syndromic diseases, termed ciliopathies. The primary cilium is therefore gaining attention due to its potential as a therapeutic target. In this review, we examine ciliary receptors, ciliogenesis, and ciliary trafficking as possible therapeutic targets. We first discuss the mechanisms of selective distribution, signal transduction, and physiological roles of ciliary receptors. Next, pathways that regulate ciliogenesis, specifically the Aurora A kinase, mammalian target of rapamycin, and ubiquitin-proteasome pathways are examined as therapeutic targets to regulate ciliogenesis. Then, in the photoreceptors, the mechanism of ciliary trafficking which takes place at the transition zone involving the ciliary membrane proteins is reviewed. Finally, some of the current therapeutic advancements highlighting the role of large animal models of photoreceptor ciliopathy are discussed.
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Affiliation(s)
- Masaki Saito
- Department of Molecular Physiology and Pathology, School of Pharma-Sciences, Teikyo University, Tokyo, Japan
| | - Wataru Otsu
- Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan
| | - Keiko Miyadera
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Yuhei Nishimura
- Department of Integrative Pharmacology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
- Mie University Research Center for Cilia and Diseases, Tsu, Mie, Japan
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3
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Zufiaurre-Seijo M, García-Arumí J, Duarri A. Clinical and Molecular Aspects of C2orf71/PCARE in Retinal Diseases. Int J Mol Sci 2023; 24:10670. [PMID: 37445847 DOI: 10.3390/ijms241310670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Mutations in the photoreceptor-specific C2orf71 gene (also known as photoreceptor cilium actin regulator protein PCARE) cause autosomal recessive retinitis pigmentosa type 54 and cone-rod dystrophy. No treatments are available for patients with C2orf71 retinal ciliopathies exhibiting a severe clinical phenotype. Our understanding of the disease process and the role of PCARE in the healthy retina significantly limits our capacity to transfer recent technical developments into viable therapy choices. This study summarizes the current understanding of C2orf71-related retinal diseases, including their clinical manifestations and an unclear genotype-phenotype correlation. It discusses molecular and functional studies on the photoreceptor-specific ciliary PCARE, focusing on the photoreceptor cell and its ciliary axoneme. It is proposed that PCARE is an actin-associated protein that interacts with WASF3 to regulate the actin-driven expansion of the ciliary membrane during the development of a new outer segment disk in photoreceptor cells. This review also introduces various cellular and animal models used to model these diseases and provides an overview of potential treatments.
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Affiliation(s)
- Maddalen Zufiaurre-Seijo
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
| | - José García-Arumí
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
| | - Anna Duarri
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
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4
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Preclinical Models of Retinitis Pigmentosa. Methods Mol Biol 2022; 2560:181-215. [PMID: 36481897 DOI: 10.1007/978-1-0716-2651-1_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Retinitis pigmentosa (RP) is the name for a group of phenotypically-related heritable retinal degenerative disorders. Many genes have been implicated as causing variants of RP, and while the clinical phenotypes are remarkably similar, they may differ in age of onset, progression, and severity. Common inheritance patterns for specific genes connected with the development of the disorder include autosomal dominant, autosomal recessive, and X-linked. Modeling the disease in animals and other preclinical systems offers a cost-conscious, ethical, and time-efficient method for studying the disease subtypes. The history of RP models is briefly examined, and both naturally occurring and transgenic preclinical models of RP in many different organisms are discussed. Syndromic forms of RP and models thereof are reviewed as well.
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5
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Urkasemsin G, Pongpanich M, Sariya L, Kongcharoen A, Buddhirongawatr R, Rungarunlert S, Ferreira JN, Chetruengchai W, Phokaew C, Srichomthong C, Shotelersuk V. Whole genome sequencing identifies a homozygous nonsense mutation in the JPH2 gene in Shih Tzu dogs with progressive retinal atrophy. Anim Genet 2021; 52:714-719. [PMID: 34231238 DOI: 10.1111/age.13118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2021] [Indexed: 11/28/2022]
Abstract
Progressive retinal atrophy (PRA), common autosomal recessive disorder affecting several dog breeds including Shih Tzu, is characterized by degeneration of photoreceptors leading to blindness. To identify PRA genetic variants, three affected and 15 unaffected Shih Tzu and 20 non-Shih Tzu were recruited. Dogs underwent ophthalmologic examination and electroretinography, revealing hallmark retina pathological changes and an abnormal electroretinography in all affected dogs but not in unaffected dogs. WGS was performed. Non-synonymous homozygous variants were searched in coding regions of genes involved in retinal diseases/development; the criterion was that variants should only be present in affected dogs and should be absent in both unaffected and 46 genomes of dogs (from an available evolutionary database). Only one out of the 109 identified variants is predicted to harbor a high-impact consequence, a nonsense c.452A>C (p.L151X) in the JPH2 gene. The genotype of JPH2 variant in all 38 dogs was determined with Sanger sequencing. All three affected dogs, but none of the 35 unaffected, were homozygous for the nonsense variant. JPH2 has been previously found to be expressed in several excitable cells/tissues including retina photoreceptors. Hence, JPH2 is a candidate gene for PRA in Shih Tzu.
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Affiliation(s)
- G Urkasemsin
- Department of Preclinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - M Pongpanich
- Department of Mathematics and Computer Science, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.,Age-related Inflammation and Degeneration Research Unit, Chulalongkorn University, Bangkok, 10330, Thailand
| | - L Sariya
- The Monitoring and Surveillance Center for Zoonotic Diseases in Wildlife and Exotic Animals, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - A Kongcharoen
- Prasu-Arthorn Animal Hospital, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - R Buddhirongawatr
- Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - S Rungarunlert
- Department of Preclinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - J N Ferreira
- Exocrine Gland Biology and Regeneration Research Group, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - W Chetruengchai
- Department of Pediatrics, Faculty of Medicine, Center of Excellence for Medical Genomics, Medical Genomics Cluster, Chulalongkorn University, Bangkok, 10330, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - C Phokaew
- Department of Pediatrics, Faculty of Medicine, Center of Excellence for Medical Genomics, Medical Genomics Cluster, Chulalongkorn University, Bangkok, 10330, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - C Srichomthong
- Department of Pediatrics, Faculty of Medicine, Center of Excellence for Medical Genomics, Medical Genomics Cluster, Chulalongkorn University, Bangkok, 10330, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - V Shotelersuk
- Department of Pediatrics, Faculty of Medicine, Center of Excellence for Medical Genomics, Medical Genomics Cluster, Chulalongkorn University, Bangkok, 10330, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
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CCDC66 frameshift variant associated with a new form of early-onset progressive retinal atrophy in Portuguese Water Dogs. Sci Rep 2020; 10:21162. [PMID: 33273526 PMCID: PMC7712861 DOI: 10.1038/s41598-020-77980-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 11/10/2020] [Indexed: 11/17/2022] Open
Abstract
Aberrant photoreceptor function or morphogenesis leads to blinding retinal degenerative diseases, the majority of which have a genetic aetiology. A variant in PRCD previously identified in Portuguese Water Dogs (PWDs) underlies prcd (progressive rod-cone degeneration), an autosomal recessive progressive retinal atrophy (PRA) with a late onset at 3–6 years of age or older. Herein, we have identified a new form of early-onset PRA (EOPRA) in the same breed. Pedigree analysis suggested an autosomal recessive inheritance. Four PWD full-siblings affected with EOPRA diagnosed at 2–3 years of age were genotyped (173,661 SNPs) along with 2 unaffected siblings, 2 unaffected parents, and 15 unrelated control PWDs. GWAS, linkage analysis and homozygosity mapping defined a 26-Mb candidate region in canine chromosome 20. Whole-genome sequencing in one affected dog and its obligatory carrier parents identified a 1 bp insertion (CFA20:g.33,717,704_33,717,705insT (CanFam3.1); c.2262_c.2263insA) in CCDC66 predicted to cause a frameshift and truncation (p.Val747SerfsTer8). Screening of an extended PWD population confirmed perfect co-segregation of this genetic variant with the disease. Western blot analysis of COS-1 cells transfected with recombinant mutant CCDC66 expression constructs showed the mutant transcript translated into a truncated protein. Furthermore, in vitro studies suggest that the mutant CCDC66 is mislocalized to the nucleus relative to wild type CCDC66. CCDC66 variants have been associated with inherited retinal degenerations (RDs) including canine and murine ciliopathies. As genetic variants affecting the primary cilium can cause ciliopathies in which RD may be either the sole clinical manifestation or part of a syndrome, our findings further support a role for CCDC66 in retinal function and viability, potentially through its ciliary function.
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7
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Hitti-Malin RJ, Burmeister LM, Ricketts SL, Lewis TW, Pettitt L, Boursnell M, Schofield EC, Sargan D, Mellersh CS. A LINE-1 insertion situated in the promoter of IMPG2 is associated with autosomal recessive progressive retinal atrophy in Lhasa Apso dogs. BMC Genet 2020; 21:100. [PMID: 32894063 PMCID: PMC7487703 DOI: 10.1186/s12863-020-00911-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 08/30/2020] [Indexed: 12/30/2022] Open
Abstract
Background Canine progressive retinal atrophies are a group of hereditary retinal degenerations in dogs characterised by depletion of photoreceptor cells in the retina, which ultimately leads to blindness. PRA in the Lhasa Apso (LA) dog has not previously been clinically characterised or described in the literature, but owners in the UK are advised to have their dog examined through the British Veterinary Association/ Kennel Club/ International Sheep Dog Society (BVA/KC/ISDS) eye scheme annually, and similar schemes that are in operation in other countries. After the exclusion of 25 previously reported canine retinal mutations in LA PRA-affected dogs, we sought to identify the genetic cause of PRA in this breed. Results Analysis of whole-exome sequencing data of three PRA-affected LA and three LA without signs of PRA did not identify any exonic or splice site variants, suggesting the causal variant was non-exonic. We subsequently undertook a genome-wide association study (GWAS), which identified a 1.3 Mb disease-associated region on canine chromosome 33, followed by whole-genome sequencing analysis that revealed a long interspersed element-1 (LINE-1) insertion upstream of the IMPG2 gene. IMPG2 has previously been implicated in human retinal disease; however, until now no canine PRAs have been associated with this gene. The identification of this PRA-associated variant has enabled the development of a DNA test for this form of PRA in the breed, here termed PRA4 to distinguish it from other forms of PRA described in other breeds. This test has been used to determine the genotypes of over 900 LA dogs. A large cohort of genotyped dogs was used to estimate the allele frequency as between 0.07–0.1 in the UK LA population. Conclusions Through the use of GWAS and subsequent sequencing of a PRA case, we have identified a LINE-1 insertion in the retinal candidate gene IMPG2 that is associated with a form of PRA in the LA dog. Validation of this variant in 447 dogs of 123 breeds determined it was private to LA dogs. We envisage that, over time, the developed DNA test will offer breeders the opportunity to avoid producing dogs affected with this form of PRA.
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Affiliation(s)
- Rebekkah J Hitti-Malin
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk, CB8 7UU, UK. .,Department of Veterinary Medicine, University of Cambridge, Cambridge, CB3 0ES, UK.
| | - Louise M Burmeister
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk, CB8 7UU, UK
| | - Sally L Ricketts
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk, CB8 7UU, UK
| | - Thomas W Lewis
- The Kennel Club, London, W1J 8AB, UK.,School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington, Leicestershire, LE12 5RD, UK
| | - Louise Pettitt
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk, CB8 7UU, UK
| | - Mike Boursnell
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk, CB8 7UU, UK
| | - Ellen C Schofield
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk, CB8 7UU, UK
| | - David Sargan
- Department of Veterinary Medicine, University of Cambridge, Cambridge, CB3 0ES, UK
| | - Cathryn S Mellersh
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk, CB8 7UU, UK
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8
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A SIX6 Nonsense Variant in Golden Retrievers with Congenital Eye Malformations. Genes (Basel) 2019; 10:genes10060454. [PMID: 31207931 PMCID: PMC6628151 DOI: 10.3390/genes10060454] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/04/2019] [Accepted: 06/11/2019] [Indexed: 12/22/2022] Open
Abstract
Causative genetic variants for more than 30 heritable eye disorders in dogs have been reported. For other clinically described eye disorders, the genetic cause is still unclear. We investigated four Golden Retriever litters segregating for highly variable congenital eye malformations. Several affected puppies had unilateral or bilateral retina dysplasia and/or optic nerve hypoplasia. The four litters shared the same father or grandfather suggesting a heritable condition with an autosomal dominant mode of inheritance. The genome of one affected dog was sequenced and compared to 601 control genomes. A heterozygous private nonsense variant, c.487C>T, was found in the SIX6 gene. This variant is predicted to truncate about a third of the open reading frame, p.(Gln163*). We genotyped all available family members and 464 unrelated Golden Retrievers. All three available cases were heterozygous. Five additional close relatives including the common sire were also heterozygous, but did not show any obvious eye phenotypes. The variant was absent from the 464 unrelated Golden Retrievers and 17 non-affected siblings of the cases. The SIX6 protein is a homeobox transcription factor with a known role in eye development. In humans and other species, SIX6 loss of function variants were reported to cause congenital eye malformations. This strongly suggests that the c.487C>T variant detected contributed to the observed eye malformations. We hypothesize that the residual amount of functional SIX6 protein likely to be expressed in heterozygous dogs is sufficient to explain the observed incomplete penetrance and the varying severity of the eye defects in the affected dogs.
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Hitti RJ, Oliver JAC, Schofield EC, Bauer A, Kaukonen M, Forman OP, Leeb T, Lohi H, Burmeister LM, Sargan D, Mellersh CS. Whole Genome Sequencing of Giant Schnauzer Dogs with Progressive Retinal Atrophy Establishes NECAP1 as a Novel Candidate Gene for Retinal Degeneration. Genes (Basel) 2019; 10:genes10050385. [PMID: 31117272 PMCID: PMC6562617 DOI: 10.3390/genes10050385] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/08/2019] [Accepted: 05/17/2019] [Indexed: 12/30/2022] Open
Abstract
Canine progressive retinal atrophies (PRA) are genetically heterogeneous diseases characterized by retinal degeneration and subsequent blindness. PRAs are untreatable and affect multiple dog breeds, significantly impacting welfare. Three out of seven Giant Schnauzer (GS) littermates presented with PRA around four years of age. We sought to identify the causal variant to improve our understanding of the aetiology of this form of PRA and to enable development of a DNA test. Whole genome sequencing of two PRA-affected full-siblings and both unaffected parents was performed. Variants were filtered based on those segregating appropriately for an autosomal recessive disorder and predicted to be deleterious. Successive filtering against 568 canine genomes identified a single nucleotide variant in the gene encoding NECAP endocytosis associated 1 (NECAP1): c.544G>A (p.Gly182Arg). Five thousand one hundred and thirty canids of 175 breeds, 10 cross-breeds and 3 wolves were genotyped for c.544G>A. Only the three PRA-affected GS were homozygous (allele frequency in GS, excluding proband family = 0.015). In addition, we identified heterozygotes belonging to Spitz and Dachshund varieties, demonstrating c.544G>A segregates in other breeds of German origin. This study, in parallel with the known retinal expression and role of NECAP1 in clathrin mediated endocytosis (CME) in synapses, presents NECAP1 as a novel candidate gene for retinal degeneration in dogs and other species.
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Affiliation(s)
- Rebekkah J Hitti
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK.
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK.
| | - James A C Oliver
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK.
| | - Ellen C Schofield
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK.
| | - Anina Bauer
- Institute of Genetics, University of Bern, 3001 Bern, Switzerland.
| | - Maria Kaukonen
- Department of Veterinary Biosciences, University of Helsinki, 00014 Helsinki, Finland.
- Department of Medical Genetics, University of Helsinki, 00014 Helsinki, Finland.
- Folkhälsan Research Center, 00290 Helsinki, Finland.
| | - Oliver P Forman
- Wisdom Health, Waltham-on-the-Wolds, Leicestershire LE14 4RS, UK.
| | - Tosso Leeb
- Institute of Genetics, University of Bern, 3001 Bern, Switzerland.
| | - Hannes Lohi
- Department of Veterinary Biosciences, University of Helsinki, 00014 Helsinki, Finland.
- Department of Medical Genetics, University of Helsinki, 00014 Helsinki, Finland.
- Folkhälsan Research Center, 00290 Helsinki, Finland.
| | - Louise M Burmeister
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK.
| | - David Sargan
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK.
| | - Cathryn S Mellersh
- Kennel Club Genetics Centre, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK.
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Natural models for retinitis pigmentosa: progressive retinal atrophy in dog breeds. Hum Genet 2019; 138:441-453. [PMID: 30904946 DOI: 10.1007/s00439-019-01999-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/14/2019] [Indexed: 01/24/2023]
Abstract
Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal disorders eventually leading to blindness with different ages of onset, progression and severity. Human RP, first characterized by the progressive degeneration of rod photoreceptor cells, shows high genetic heterogeneity with more than 90 genes identified. However, about one-third of patients have no known genetic causes. Interestingly, dogs are also severely affected by similar diseases, called progressive retinal atrophy (PRA). Indeed, RP and PRA have comparable clinical signs, physiopathology and outcomes, similar diagnosis methods and most often, orthologous genes are involved. The many different dog PRAs often segregate in specific breeds. Indeed, undesired alleles have been selected and amplified through drastic selection and excessive use of inbreeding. Out of the 400 breeds, nearly 100 have an inherited form of PRA, which are natural animal models that can be used to investigate the genetics, disease progression and therapies in dogs for the benefit of both dogs and humans. Recent knowledge on the canine genome and access to new genotyping and sequencing technologies now efficiently allows the identification of mutations involved in canine genetic diseases. To date, PRA genes identified in dog breeds correspond to the same genes in humans and represent relevant RP models, and new genes found in dogs represent good candidate for still unknown human RP. We present here a review of the main advantages of the dog models for human RP with the genes already identified and an X-linked PRA in the Border collie as a model for orphan X-linked RPs in human.
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11
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Complex Structural PPT1 Variant Associated with Non-syndromic Canine Retinal Degeneration. G3-GENES GENOMES GENETICS 2019; 9:425-437. [PMID: 30541930 PMCID: PMC6385984 DOI: 10.1534/g3.118.200859] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rod and cone photoreceptors are specialized retinal neurons that have a fundamental role in visual perception, capturing light and transducing it into a neuronal signal. Aberrant functioning of rod and/or cone photoreceptors can ultimately lead to progressive degeneration and eventually blindness. In man, many rod and rod-cone degenerative diseases are classified as forms of retinitis pigmentosa (RP). Dogs also have a comparable disease grouping termed progressive retinal atrophy (PRA). These diseases are generally due to single gene defects and follow Mendelian inheritance.We collected 51 DNA samples from Miniature Schnauzers affected by PRA (average age of diagnosis ∼3.9 ±1 years), as well as from 56 clinically normal controls of the same breed (average age ∼6.6 ±2.8 years). Pedigree analysis suggested monogenic autosomal recessive inheritance of PRA. GWAS and homozygosity mapping defined a critical interval in the first 4,796,806 bp of CFA15. Whole genome sequencing of two affected cases, a carrier and a control identified two candidate variants within the critical interval. One was an intronic SNV in HIVEP3, and the other was a complex structural variant consisting of the duplication of exon 5 of the PPT1 gene along with a conversion and insertion (named PPT1dci). PPT1dci was confirmed homozygous in a cohort of 22 cases, and 12 more cases were homozygous for the CFA15 haplotype. Additionally, the variant was found homozygous in 6 non-affected dogs of age higher than the average age of onset. The HIVEP3 variant was found heterozygous (n = 4) and homozygous wild-type (n = 1) in cases either homozygous for PPT1dci or for the mapped CFA15 haplotype. We detected the wildtype and three aberrant PPT1 transcripts in isolated white blood cell mRNA extracted from a PRA case homozygous for PPT1dci, and the aberrant transcripts involved inclusion of the duplicated exon 5 and novel exons following the activation of cryptic splice sites. No neurological signs were detected among the dogs homozygous for the PPT1dci variant. Therefore, we propose PPT1dci as causative for a non-syndromic form of PRA (PRAPPT1) that shows incomplete penetrance in Miniature Schnauzers, potentially related to the presence of the wild-type transcript. To our knowledge, this is the first case of isolated retinal degeneration associated with a PPT1 variant.
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Lewis TW, Mellersh CS. Changes in mutation frequency of eight Mendelian inherited disorders in eight pedigree dog populations following introduction of a commercial DNA test. PLoS One 2019; 14:e0209864. [PMID: 30650096 PMCID: PMC6334900 DOI: 10.1371/journal.pone.0209864] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/12/2018] [Indexed: 12/24/2022] Open
Abstract
Introduction DNA testing for autosomal recessive disease mutations in many dog breeds is now relatively commonplace. There have, however, been few efforts made to determine changes in the frequency of disease causing mutations as a result of probable selection based on the results of DNA testing. This study makes use of genotype data from both DNA test results reported to the UK Kennel Club and where known from a ‘hereditary status’ (where a definitive genotype may be inferred and ascribed based on known parental genotypes) to do so. Results The results, using all known genotype data, show a general and sizeable decline in disease causing mutation frequency across eight diseases in eight breeds (by between 12–86% in dogs born 2–4 years after publication of the mutation, and by nearly 90% or more in those born 8–10 years after). In contrast, data from test results only, while revealing an almost complete and immediate end to the production of affected individuals, show little general decline in either the derived mutation frequency or the proportion of heterozygote carriers. It appears that the numerical size of the breed is an important determinant on the rate of uptake of a DNA test (as judged by the proportion of a breed born four years after publication of the disease-causing mutation with a known genotype). Conclusion These results show that dog breeders appear to be incorporating the results of DNA testing into their selection strategies to successfully decrease the frequency of the mutation. It is shown that use of DNA test result data alone does not reveal such trends, possibly as some breeders undertake testing to determine clear stock which can then be used to produce future disease-free generations in the knowledge they are not carrying the disease causing mutation.
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Affiliation(s)
- T. W. Lewis
- The Kennel Club, London, England
- School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, England
- * E-mail:
| | - C. S. Mellersh
- The Kennel Club Genetics Centre at the Animal Health Trust, Kentford, Newmarket, Suffolk, England
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13
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Baehr W, Hanke-Gogokhia C, Sharif A, Reed M, Dahl T, Frederick JM, Ying G. Insights into photoreceptor ciliogenesis revealed by animal models. Prog Retin Eye Res 2018; 71:26-56. [PMID: 30590118 DOI: 10.1016/j.preteyeres.2018.12.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 12/10/2018] [Accepted: 12/18/2018] [Indexed: 12/11/2022]
Abstract
Photoreceptors are polarized neurons, with very specific subcellular compartmentalization and unique requirements for protein expression and trafficking. Each photoreceptor contains an outer segment, the site of photon capture that initiates vision, an inner segment that houses the biosynthetic machinery and a synaptic terminal for signal transmission to downstream neurons. Outer segments and inner segments are connected by a connecting cilium (CC), the equivalent of a transition zone (TZ) of primary cilia. The connecting cilium is part of the basal body/axoneme backbone that stabilizes the outer segment. This report will update the reader on late developments in photoreceptor ciliogenesis and transition zone formation, specifically in mouse photoreceptors, focusing on early events in photoreceptor ciliogenesis. The connecting cilium, an elongated and narrow structure through which all outer segment proteins and membrane components must traffic, functions as a gate that controls access to the outer segment. Here we will review genes and their protein products essential for basal body maturation and for CC/TZ genesis, sorted by phenotype. Emphasis is given to naturally occurring mouse mutants and gene knockouts that interfere with CC/TZ formation and ciliogenesis.
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Affiliation(s)
- Wolfgang Baehr
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA.
| | - Christin Hanke-Gogokhia
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Ali Sharif
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Michelle Reed
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Tiffanie Dahl
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Jeanne M Frederick
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Guoxin Ying
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
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14
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Karlskov-Mortensen P, Proschowsky HF, Gao F, Fredholm M. Identification of the mutation causing progressive retinal atrophy in Old Danish Pointing Dog. Anim Genet 2018; 49:237-241. [DOI: 10.1111/age.12659] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2018] [Indexed: 12/23/2022]
Affiliation(s)
- P. Karlskov-Mortensen
- Animal Genetics, Bioinformatics & Breeding; Department of Veterinary & Animal Sciences; Faculty of Health & Medical Sciences; University of Copenhagen; Grønnegårdsvej 3 DK-1870 Frederiksberg C Denmark
| | | | - F. Gao
- Agricultural Genomes Institute at Shenzhen; Chinese Agricultural Academy of Sciences; Shenzhen China
| | - M. Fredholm
- Animal Genetics, Bioinformatics & Breeding; Department of Veterinary & Animal Sciences; Faculty of Health & Medical Sciences; University of Copenhagen; Grønnegårdsvej 3 DK-1870 Frederiksberg C Denmark
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15
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Miyadera K. Mapping of Canine Models of Inherited Retinal Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1074:257-264. [PMID: 29721951 DOI: 10.1007/978-3-319-75402-4_31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The gene/mutation discovery approaches for inherited retinal diseases (RDs) in the dog model have seen considerable development over the past 25 years. Initial attempts were focused on candidate genes, followed by genome-wide approaches including linkage analysis and DNA-chip-based genome-wide association study. Combined, there are as many as 32 mutations in 27 genes that have been associated with canine retinal diseases to date. More recently, next-generation sequencing has become one of the key methods of choice. With increasing knowledge of the molecular basis of RDs and follow-up surveys in different subpopulations, the conventional understanding of RDs as simple Mendelian traits is being challenged. Modifiers and involvement of multiple genes that alter the disease expression are complicating the prediction of the disease course. In this chapter, advances in the gene/mutation discovery approaches for canine RDs are reviewed, and a multigenic form of canine RD is discussed using a form of canine cone-rod dystrophy as an example.
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Affiliation(s)
- Keiko Miyadera
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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16
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Guandalini A, Di Girolamo N, Corvi R, Santillo D, Andreani V, Pinzo B. Epidemiology of ocular disorders presumed to be inherited in three small Italian dog breeds in Italy. Vet Ophthalmol 2017; 21:524-529. [PMID: 29284193 DOI: 10.1111/vop.12542] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To describe the prevalence and the types of eye disorders that are known or presumed to be inherited (KP-HED) in three small Italian dog breeds. ANIMALS Three small Italian dog breeds: Maltese, Bolognese, and Italian Greyhound. PROCEDURES All dogs of the breeds selected for this prospective observational study that underwent a complete ophthalmic examination between 1994 and 2015 were included. General and proportional KP-HED prevalence with 95% confidence intervals were reported. RESULTS Three hundred and six of 462 dogs were affected by at least one KP-HED (66.2%; 95% CI: 61.8%-70.4%). In the entire population, the five most common KP-HED were cataract (n = 122; rate on the total number of KP-HED: 31.4%), entropion (n = 56; 14.4%), keratoconjunctivitis sicca (n = 33; 8.5%), retinal dysplasia (n = 24; 6.2%), and persistent pupillary membrane (iris to iris) (n = 21; 5.4%). The most common KP-HED in each breed were cataracts in the Maltese (35.1%) and in the Bolognese (24.2%), and presentation of vitreous in the anterior chamber in the Italian Greyhound (46.7%). CONCLUSIONS Clinicians should be aware of KP-HED that commonly affect three small Italian dog breeds. Breed standards should be reconsidered, and breeding programs should be directed at limiting such disorders.
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Affiliation(s)
- Adolfo Guandalini
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 51/53, 00137, Rome, Italy
| | - Nicola Di Girolamo
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 51/53, 00137, Rome, Italy.,EBMVet, Via Sigismondo Trecchi 20, Cremona, Italy
| | - Roberta Corvi
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 51/53, 00137, Rome, Italy
| | - Daniele Santillo
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 51/53, 00137, Rome, Italy
| | - Valentina Andreani
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 51/53, 00137, Rome, Italy
| | - Barbara Pinzo
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 51/53, 00137, Rome, Italy
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Everson R, Pettitt L, Forman OP, Dower-Tylee O, McLaughlin B, Ahonen S, Kaukonen M, Komáromy AM, Lohi H, Mellersh CS, Sansom J, Ricketts SL. An intronic LINE-1 insertion in MERTK is strongly associated with retinopathy in Swedish Vallhund dogs. PLoS One 2017; 12:e0183021. [PMID: 28813472 PMCID: PMC5558984 DOI: 10.1371/journal.pone.0183021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 07/30/2017] [Indexed: 12/31/2022] Open
Abstract
The domestic dog segregates a significant number of inherited progressive retinal diseases, several of which mirror human retinal diseases and which are collectively termed progressive retinal atrophy (PRA). In 2014, a novel form of PRA was reported in the Swedish Vallhund breed, and the disease was mapped to canine chromosome 17. The causal mutation was not identified, but expression analyses of the retinas of affected Vallhunds demonstrated a 6-fold increased expression of the MERTK gene compared to unaffected dogs. Using 24 retinopathy cases and 97 controls with no clinical signs of retinopathy, we replicated the chromosome 17 association in Swedish Vallhunds from the UK and aimed to elucidate the causal variant underlying this association using whole genome sequencing (WGS) of an affected dog. This revealed a 6-8 kb insertion in intron 1 of MERTK that was not present in WGS of 49 dogs of other breeds. Sequencing and BLASTN analysis of the inserted segment was consistent with the insertion comprising a full-length intact LINE-1 retroelement. Testing of the LINE-1 insertion for association with retinopathy in the UK set of 24 cases and 97 controls revealed a strong statistical association (P-value 6.0 x 10-11) that was subsequently replicated in the original Finnish study set (49 cases and 89 controls (P-value 4.3 x 10-19). In a pooled analysis of both studies (73 cases and 186 controls), the LINE-1 insertion was associated with a ~20-fold increased risk of retinopathy (odds ratio 23.41, 95% confidence intervals 10.99-49.86, P-value 1.3 x 10-27). Our study adds further support for regulatory disruption of MERTK in Swedish Vallhund retinopathy; however, further work is required to establish a functional overexpression model. Future work to characterise the mechanism by which this intronic mutation disrupts gene regulation will further improve the understanding of MERTK biology and its role in retinal function.
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Affiliation(s)
- Richard Everson
- Centre for Small Animal Studies–Ophthalmology Unit, Animal Health Trust, Kentford, Newmarket, Suffolk, United Kingdom
| | - Louise Pettitt
- Canine Genetics Research Group, Kennel Club Genetics Centre, Animal Health Trust, Kentford, Newmarket, Suffolk, United Kingdom
| | - Oliver P. Forman
- Canine Genetics Research Group, Kennel Club Genetics Centre, Animal Health Trust, Kentford, Newmarket, Suffolk, United Kingdom
| | - Olivia Dower-Tylee
- Canine Genetics Research Group, Kennel Club Genetics Centre, Animal Health Trust, Kentford, Newmarket, Suffolk, United Kingdom
| | - Bryan McLaughlin
- Canine Genetics Research Group, Kennel Club Genetics Centre, Animal Health Trust, Kentford, Newmarket, Suffolk, United Kingdom
| | - Saija Ahonen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Maria Kaukonen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - András M. Komáromy
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hannes Lohi
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Cathryn S. Mellersh
- Canine Genetics Research Group, Kennel Club Genetics Centre, Animal Health Trust, Kentford, Newmarket, Suffolk, United Kingdom
| | - Jane Sansom
- Centre for Small Animal Studies–Ophthalmology Unit, Animal Health Trust, Kentford, Newmarket, Suffolk, United Kingdom
| | - Sally L. Ricketts
- Canine Genetics Research Group, Kennel Club Genetics Centre, Animal Health Trust, Kentford, Newmarket, Suffolk, United Kingdom
- * E-mail:
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18
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Genetic characterization and disease mechanism of retinitis pigmentosa; current scenario. 3 Biotech 2017; 7:251. [PMID: 28721681 DOI: 10.1007/s13205-017-0878-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 07/10/2017] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa is a group of genetically transmitted disorders affecting 1 in 3000-8000 individual people worldwide ultimately affecting the quality of life. Retinitis pigmentosa is characterized as a heterogeneous genetic disorder which leads by progressive devolution of the retina leading to a progressive visual loss. It can occur in syndromic (with Usher syndrome and Bardet-Biedl syndrome) as well as non-syndromic nature. The mode of inheritance can be X-linked, autosomal dominant or autosomal recessive manner. To date 58 genes have been reported to associate with retinitis pigmentosa most of them are either expressed in photoreceptors or the retinal pigment epithelium. This review focuses on the disease mechanisms and genetics of retinitis pigmentosa. As retinitis pigmentosa is tremendously heterogeneous disorder expressing a multiplicity of mutations; different variations in the same gene might induce different disorders. In recent years, latest technologies including whole-exome sequencing contributing effectively to uncover the hidden genesis of retinitis pigmentosa by reporting new genetic mutations. In future, these advancements will help in better understanding the genotype-phenotype correlations of disease and likely to develop new therapies.
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19
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Somma AT, Moreno JCD, Sato MT, Rodrigues BD, Bacellar-Galdino M, Occelli LM, Petersen-Jones SM, Montiani-Ferreira F. Characterization of a novel form of progressive retinal atrophy in Whippet dogs: a clinical, electroretinographic, and breeding study. Vet Ophthalmol 2016; 20:450-459. [PMID: 27896899 DOI: 10.1111/vop.12448] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To describe a form of progressive retinal atrophy (PRA) in Whippets including clinical, electroretinographic, optical coherence tomographic changes and pedigree analysis. ANIMALS STUDIED Client-owned Whippet dogs (n = 51) living in Brazil. PROCEDURES All animals were submitted for routine ophthalmic screening for presumed inherited ocular disease, which included the following: visual tests, such as obstacle course tests, in scotopic and photopic conditions, cotton ball test, dazzle reflex, ocular fundus evaluation by indirect ophthalmoscopy followed by fundus photography. Additionally, electroretinography (ERG) and optical coherence tomography (OCT) were performed in 24 and four dogs, respectively. RESULTS Sixteen dogs were diagnosed with PRA. Vision deficits in dim light were detected in dogs examined at a young age associated with nystagmus. Funduscopic changes included the development of multifocal retinal bullae from 6 months of age. Retinal thinning became apparent later, at which time the bullae were no longer detected. OCT examination of selected young dogs revealed that the retinal bullae were due to separation between photoreceptors and the retinal pigment epithelium, and of dogs with more advanced disease confirmed the development of retinal thinning. Electroretinography in young dogs revealed a negative ERG due to a lack of b-wave in both scotopic and photopic recordings. With progression, the ERG became unrecordable. Pedigree analysis suggested an autosomal recessive mode of inheritance. CONCLUSION The retinal dystrophy reported here in Whippet dogs has a unique phenotype of an initial lack of ERG b-wave, development of retinal bullae then a progressive generalized retinal degeneration.
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Affiliation(s)
- André Tavares Somma
- Veterinary Medicine Department, Comparative Ophthalmology Laboratory, Rua dos Funcionários, 1540, Curtiba, 80035-050, Brazil
| | - Juan Carlos Duque Moreno
- Veterinary Medicine Department, Comparative Ophthalmology Laboratory, Rua dos Funcionários, 1540, Curtiba, 80035-050, Brazil
| | - Mario Teruo Sato
- Universidade Federal do Parana, R. Padre Camargo, 280, Curtiba, 80060-240, Brazil
| | - Blanche Dreher Rodrigues
- Ophthalmology Service, Centro Integrado de Especialidades Veterinárias, Rua André Zanetti, 144, Curtiba, 808010-280, Brazil
| | - Marianna Bacellar-Galdino
- Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road D-208, East Lansing, MI, 48824, USA
| | - Laurence Mireille Occelli
- Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road D-208, East Lansing, MI, 48824, USA
| | - Simon Michael Petersen-Jones
- Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road D-208, East Lansing, MI, 48824, USA
| | - Fabiano Montiani-Ferreira
- Veterinary Medicine Department, Comparative Ophthalmology Laboratory, Rua dos Funcionários, 1540, Curtiba, 80035-050, Brazil
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20
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Guandalini A, Di Girolamo N, Santillo D, Andreani V, Corvi R, Bandini M, Peruccio C. Epidemiology of ocular disorders presumed to be inherited in three large Italian dog breeds in Italy. Vet Ophthalmol 2016; 20:420-426. [PMID: 27860098 DOI: 10.1111/vop.12442] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To describe the epidemiology and the types of eye disorders that are presumed to be inherited (PIED) in three large Italian dog breeds. ANIMALS Three large Italian dog breeds: Neapolitan Mastiff (FCI code: 197), Maremma Sheepdog (FCI code: 201), and Italian Corso dog (FCI code: 343). PROCEDURES All dogs that underwent a complete ophthalmic examination between 1992 and 2012 were included in this prospective observational study. The prevalence of eye disorders with 95% confidence intervals was reported for presumed healthy dogs and for dogs referred to a veterinary center for an ophthalmic consultation. Univariate and multivariate logistic regression techniques were used to generate odds ratios. RESULTS Of 605 dogs examined during the study period, 351 dogs were affected by at least one PIED (58%; 95% CI: 54-62%). The prevalence of PIED was significantly lower in dogs presented for ophthalmic examination (53.8%) as compared to presumed healthy dogs (62.2%)(OR: 1.4; 95% CI: 1.02-1.9; P = 0.037). Also after multivariate adjustment for the period of observation, the odds of Neapolitan Mastiff (92.1%; OR: 21.4; 95% CI: 11.1-41.4) and of Cane Corso (57.7%; OR: 2.5; 95% CI: 1.7-3.6) suffering a PIED were greater than the Maremma Sheepdog (35.4%). The most common PIED in each breed were entropion (24.3% of all the PIED) in the Neapolitan Mastiff, ectropion (36.6%) in the Corso dog, and cataract (27.9%) in the Maremma Sheepdog. CONCLUSIONS Clinicians should be aware that three large Italian dog breeds frequently suffer PIED. Breed standards should be reconsidered, and breeding programs should be directed at limiting such disorders.
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Affiliation(s)
- Adolfo Guandalini
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 53, Rome, 00137, Italy
| | - Nicola Di Girolamo
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 53, Rome, 00137, Italy.,Department of Veterinary Sciences, University of Bologna, Via Tolara di Sopra, 50, Ozzano dell'Emilia, Bologna, 40064, Italy
| | - Daniele Santillo
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 53, Rome, 00137, Italy
| | - Valentina Andreani
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 53, Rome, 00137, Italy
| | - Roberta Corvi
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 53, Rome, 00137, Italy.,Department of Veterinary Sciences, University of Teramo, Strada Provinciale 18 snc, Piano d'Accio, Teramo, 64100, Italy
| | - Marina Bandini
- Department of Ophthalmology, Centro Veterinario Specialistico (CVS), Via Sandro Giovannini 53, Rome, 00137, Italy
| | - Claudio Peruccio
- Ophthalmology, Centro Veterinario Torinese, Lungo Dora Pietro Colletta 147, Torino, 10153, Italy
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21
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Winkler PA, Davis JA, Petersen-Jones SM, Venta PJ, Bartoe JT. A tool set to allow rapid screening of dog families with PRA for association with candidate genes. Vet Ophthalmol 2016; 20:372-376. [DOI: 10.1111/vop.12401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Paige A. Winkler
- Department of Small Animal Clinical Sciences; College of Veterinary Medicine; Michigan State University; East Lansing MI 48824 USA
- Genetics Program; Michigan State University; East Lansing MI 48824 USA
| | - Jennifer A. Davis
- Psychiatry and Behavioral Neurobiology; University of Alabama at Birmingham; Birmingham AL 35294 USA
| | - Simon M. Petersen-Jones
- Department of Small Animal Clinical Sciences; College of Veterinary Medicine; Michigan State University; East Lansing MI 48824 USA
- Genetics Program; Michigan State University; East Lansing MI 48824 USA
| | - Patrick J. Venta
- Department of Small Animal Clinical Sciences; College of Veterinary Medicine; Michigan State University; East Lansing MI 48824 USA
- Genetics Program; Michigan State University; East Lansing MI 48824 USA
- Microbiology & Molecular Genetics; Michigan State University; East Lansing MI 48824 USA
| | - Joshua T. Bartoe
- Department of Small Animal Clinical Sciences; College of Veterinary Medicine; Michigan State University; East Lansing MI 48824 USA
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22
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Palanova A. The genetics of inherited retinal disorders in dogs: implications for diagnosis and management. VETERINARY MEDICINE-RESEARCH AND REPORTS 2016; 7:41-51. [PMID: 30050836 PMCID: PMC6042528 DOI: 10.2147/vmrr.s63537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Dogs are affected by many hereditary diseases just as humans are. One group of these diseases comprises of retinal disorders, which are a growing problem in canine breeding. These disorders are heterogeneous, with diverse causative mutations and modes of inheritance. Some affect only one breed, while others may affect many breeds; some breeds are affected by only one disease, while others can be affected by two or more. Dog breeders should take into account the presence of any deleterious alleles when choosing parents for the next generation.
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Affiliation(s)
- Anna Palanova
- Department of Tumor Biology, Institute of Animal Physiology and Genetics, v. v. i., Academy of Sciences of the Czech Republic, Libechov, Czech Republic,
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23
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Good KL, Komáromy AM, Kass PH, Ofri R. Novel retinopathy in related Gordon setters: a clinical, behavioral, electrophysiological, and genetic investigation. Vet Ophthalmol 2015; 19:398-408. [PMID: 26417729 DOI: 10.1111/vop.12315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To conduct ophthalmic, behavioral, electrophysiological, and genetic testing on two related Gordon setters presented for day blindness and compare findings with those of nine related and unrelated Gordon setters. METHODS All dogs underwent comprehensive ophthalmic examination. Maze testing was conducted under different light intensities. Rod and cone function was assessed electroretinographically. DNA samples were screened for five canine retinal disease gene mutations. RESULTS Ophthalmic examination was unremarkable in all dogs. There was no notable difference between day blind dogs and the reference population in scotopic and mesopic maze tests. Day blind dogs performed worse in the photopic maze with slower course completion time and more obstacle collisions. Electroretinography revealed extinguished cone function in day blind dogs and depressed rod responses in all but two reference dogs. One reference population dog presented with day blindness 1 year after initial examination. Mutations that cause achromatopsia (in CNGB3) and cone-rod dystrophies (in ADAM9 and IQCB1) were not detected in any dog tested, although five reference dogs were carriers of the mutation in C2orf71 that causes rod-cone degeneration 4 (rcd4) in Gordon setters and in polski owczarek nizinny dogs. CONCLUSIONS This report describes a novel retinopathy in related Gordon setters that has clinical signs and vision testing results consistent with achromatopsia but electroretinographic results suggestive of cone-rod dystrophy. The majority of Gordon setters in this study had low rod responses on electroretinography but it is unclear whether this was indicative of rod dysfunction or normal for the breed. Longer-term observation of affected individuals is warranted.
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Affiliation(s)
- Kathryn L Good
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA.
| | - András M Komáromy
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.,Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - Philip H Kass
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California- Davis, Davis, CA, 95616, USA
| | - Ron Ofri
- Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, 7610001, Israel
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24
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Wiik AC, Ropstad EO, Ekesten B, Karlstam L, Wade CM, Lingaas F. Progressive retinal atrophy in Shetland sheepdog is associated with a mutation in the CNGA1 gene. Anim Genet 2015. [PMID: 26202106 DOI: 10.1111/age.12323] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Progressive retinal atrophy (PRA) is the collective name of a class of hereditary retinal dystrophies in the dog and is often described as the equivalent of retinitis pigmentosa in humans. PRA is characterized by visual impairment due to degeneration of the photoreceptors in the retina, usually leading to blindness. PRA has been reported in dogs from more than 100 breeds and can be genetically heterogeneous both between and within breeds. The disease can be subdivided by age at onset and rate of progression. Using genome-wide association with 15 Shetland Sheepdog (Sheltie) cases and 14 controls, we identified a novel PRA locus on CFA13 (Praw = 8.55 × 10(-7) , Pgenome = 1.7 × 10(-4) ). CNGA1, which is known to be involved in human cases of retinitis pigmentosa, was located within the associated region and was considered a likely candidate gene. Sequencing of this gene identified a 4-bp deletion in exon 9 (c.1752_1755delAACT), leading to a frameshift and a premature stop codon. The study indicated genetic heterogeneity as the mutation was present in all PRA-affected individuals in one large family of Shelties, whereas some other cases in the studied Sheltie population were not associated with this CNGA1 mutation. To our knowledge, this is the first report of a mutation in CNGA1 causing PRA in dogs.
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Affiliation(s)
- A C Wiik
- Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, NMBU, Postboks 8146 Dep, 0033, Oslo, Norway
| | - E O Ropstad
- Department of Companion Animal Clinical Sciences, Norwegian University of Life Sciences, NMBU, Postboks 8146 Dep, 0033, Oslo, Norway
| | - B Ekesten
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden
| | - L Karlstam
- Aros Veterinär Centrum, Olof Palmes Torg 10, 723 34, Västerås, Sweden
| | - C M Wade
- Faculty of Veterinary Science, The University of Sydney, Sydney, NSW, 2006, Australia
| | - F Lingaas
- Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, NMBU, Postboks 8146 Dep, 0033, Oslo, Norway
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Svensson M, Olsén L, Winkler PA, Petersen-Jones SM, Bergström T, Garncarz Y, Narfström K. Progressive retinal atrophy in the Polski Owczarek Nizinny dog: a clinical and genetic study. Vet Ophthalmol 2015; 19:195-205. [PMID: 26009980 DOI: 10.1111/vop.12284] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To describe ophthalmic, functional, structural, and genetical characteristics of progressive retinal atrophy (PRA) in the polski owczarek nizinny (PON) breed of dog. ANIMALS STUDIED CLINICALLY Client-owned PON dogs (n = 82) from Sweden. PROCEDURES Routine examination for presumed inherited eye disease was performed in all dogs. Bilateral full-field electroretinography (ERG) was performed in 11 affected and 4 control dogs. Eyes from one affected dog were studied with light microscopy. DNA samples from 34 Swedish and 30 PON dogs collected by Michigan State University (MSU) were tested for the mutations causing the rcd4 and prcd forms of PRA. RESULTS Sixteen of the eighty-two Swedish dogs were diagnosed with PRA. Slight vascular attenuation, first seen at 4.5 years of age, preceded changes in tapetal reflectivity. The initial ERG changes in affected dogs showed markedly diminished rod responses, while cone responses were barely affected. Eventually, cone responses were also reduced. Retinal morphology showed approximately a 50% reduction of photoreceptor nuclei in the outer nuclear layer. Fourteen of fifteen PRA-affected Swedish dogs and eighteen of twenty of the MSU PRA-affected dogs tested genetically were positive for the rcd4 mutation. All tested dogs were negative for the mutation causing prcd-PRA. CONCLUSIONS PRA of PON dogs is a late-onset degenerative disease with slow progression. There is early loss of rod function, while the cone system deteriorates later. The rcd4 mutation in the C2ORF71 gene was associated with the majority of the PRA cases tested. The possibility of additional forms of PRA in the breed cannot be excluded.
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Affiliation(s)
- Marika Svensson
- Blue Star Animal Hospital, Gjutjärnsgatan 4, Gothenburg, 417 07, Sweden
| | - Lena Olsén
- Division of Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, SE-750 07, Sweden
| | - Paige A Winkler
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road D, 208, East Lansing, MI, USA.,Genetics Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Simon M Petersen-Jones
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road D, 208, East Lansing, MI, USA.,Genetics Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Tomas Bergström
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Yacek Garncarz
- Veterinary Eye Clinic, Grupy AK Polnoc 2/u10, Warsaw, 00-713, Poland
| | - Kristina Narfström
- College of Veterinary Medicine, 900 East Campus Drive, Columbia, MO, 65211, USA.,Retvet KB, Karlsuddsvägen 14b, Vaxholm, 185 93, Sweden
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Petersen-Jones SM, Komáromy AM. Dog models for blinding inherited retinal dystrophies. HUM GENE THER CL DEV 2015; 26:15-26. [PMID: 25671556 DOI: 10.1089/humc.2014.155] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Spontaneous canine models exist for several inherited retinal dystrophies. This review will summarize the models and indicate where they have been used in translational gene therapy trials. The RPE65 gene therapy trials to treat childhood blindness are a good example of how studies in dogs have contributed to therapy development. Outcomes in human clinical trials are compared and contrasted with the result of the preclinical dog trials.
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Affiliation(s)
- Simon M Petersen-Jones
- 1 Department of Small Animal Clinical Sciences, Michigan State University , East Lansing, MI 48824
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27
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Petersen-Jones S, Komaromy AM. Dog Models for Blinding Inherited Retinal Degenerations. HUM GENE THER CL DEV 2014. [DOI: 10.1089/hum.2014.155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Ahonen SJ, Arumilli M, Seppälä E, Hakosalo O, Kaukonen MK, Komáromy AM, Lohi H. Increased expression of MERTK is associated with a unique form of canine retinopathy. PLoS One 2014; 9:e114552. [PMID: 25517981 PMCID: PMC4269413 DOI: 10.1371/journal.pone.0114552] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/10/2014] [Indexed: 01/25/2023] Open
Abstract
Progressive retinal degenerations are among the most common causes of blindness both in human and in dogs. Canine progressive retinal atrophy (PRA) resembles human retinitis pigmentosa (RP) and is typically characterized by a progressive loss of rod photoreceptors followed by a loss of cone function. The disease gradually progress from the loss of night and day vision to a complete blindness. We have recently described a unique form of retinopathy characterized by the multifocal gray/brown discoloration and thinning of the retina in the Swedish Vallhund (SV) breed. We aimed to identify the genetic cause by performing a genome wide association analysis in a cohort of 18 affected and 10 healthy control dogs using Illumina's canine 22k SNP array. We mapped the disease to canine chromosome 17 (p = 7.7×10−5) and found a 6.1 Mb shared homozygous region in the affected dogs. A combined analysis of the GWAS and replication data with additional 60 dogs confirmed the association (p = 4.3×10−8, OR = 11.2 for homozygosity). A targeted resequencing of the entire associated region in four cases and four controls with opposite risk haplotypes identified several variants in the coding region of functional candidate genes, such as a known retinopathy gene, MERTK. However, none of the identified coding variants followed a compelling case- or breed-specific segregation pattern. The expression analyses of four candidate genes in the region, MERTK, NPHP1, ANAPC1 and KRCC1, revealed specific upregulation of MERTK in the retina of the affected dogs. Collectively, these results indicate that the retinopathy is associated with overexpression of MERTK, however further investigation is needed to discover the regulatory mutation for the better understanding of the disease pathogenesis. Our study establishes a novel gain-of-function model for the MERTK biology and provides a therapy model for retinopathy MERTK inhibitors. Meanwhile, a marker-based genetic counseling can be developed to revise breeding programs.
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Affiliation(s)
- Saija J. Ahonen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Meharji Arumilli
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Eija Seppälä
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Osmo Hakosalo
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Maria K. Kaukonen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - András M. Komáromy
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hannes Lohi
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
- * E-mail:
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Forman OP, Mellersh CS. Investigating inherited diseases in dogs. Vet Rec 2014; 174:512. [DOI: 10.1136/vr.g3295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Oliver P. Forman
- Kennel Club Genetics Centre; Animal Health Trust, Kentford Newmarket Suffolk CB87UU
| | - Cathryn S. Mellersh
- Kennel Club Genetics Centre; Animal Health Trust, Kentford Newmarket Suffolk CB87UU
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Mellersh CS. The genetics of eye disorders in the dog. Canine Genet Epidemiol 2014; 1:3. [PMID: 26401320 PMCID: PMC4574392 DOI: 10.1186/2052-6687-1-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 03/06/2014] [Indexed: 11/10/2022] Open
Abstract
Inherited forms of eye disease are arguably the best described and best characterized of all inherited diseases in the dog, at both the clinical and molecular level and at the time of writing 29 different mutations have been documented in the scientific literature that are associated with an inherited ocular disorder in the dog. The dog has already played an important role in the identification of genes that are important for ocular development and function as well as emerging therapies for inherited blindness in humans. Similarities in disease phenotype and eye structure and function between dog and man, together with the increasingly sophisticated genetic tools that are available for the dog, mean that the dog is likely to play an ever increasing role in both our understanding of the normal functioning of the eye and in our ability to treat inherited eye disorders. This review summarises the mutations that have been associated with inherited eye disorders in the dog.
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Downs LM, Mellersh CS. An Intronic SINE insertion in FAM161A that causes exon-skipping is associated with progressive retinal atrophy in Tibetan Spaniels and Tibetan Terriers. PLoS One 2014; 9:e93990. [PMID: 24705771 PMCID: PMC3976383 DOI: 10.1371/journal.pone.0093990] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/10/2014] [Indexed: 11/19/2022] Open
Abstract
Progressive retinal atrophy (PRA) in dogs is characterised by the degeneration of the photoreceptor cells of the retina, resulting in vision loss and eventually complete blindness. The condition affects more than 100 dog breeds and is known to be genetically heterogeneous between breeds. Around 19 mutations have now been identified that are associated with PRA in around 49 breeds, but for the majority of breeds the mutation(s) responsible have yet to be identified. Using genome-wide association with 22 Tibetan Spaniel PRA cases and 10 controls, we identified a novel PRA locus, PRA3, on CFA10 (praw = 2.01×10−5, pgenome = 0.014), where a 3.8 Mb region was homozygous within 12 cases. Using targeted next generation sequencing, a short interspersed nuclear element insertion was identified near a splice acceptor site in an intron of a provocative gene, FAM161A. Analysis of mRNA from an affected dog revealed that the SINE causes exon skipping, resulting in a frame shift, leading to a downstream premature termination codon and possibly a truncated protein product. This mutation segregates with the disease in 22 out of 35 cases tested (63%). Of the PRA controls, none are homozygous for the mutation, 15% carry the mutation and 85% are homozygous wildtype. This mutation was also identified in Tibetan Terriers, although our results indicate that PRA is genetically heterogeneous in both Tibetan Spaniels and Tibetan Terriers.
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Affiliation(s)
- Louise M. Downs
- Kennel Club Genetics Centre, Animal Health Trust, Newmarket, United Kingdom
| | - Cathryn S. Mellersh
- Kennel Club Genetics Centre, Animal Health Trust, Newmarket, United Kingdom
- * E-mail:
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Wheway G, Parry DA, Johnson CA. The role of primary cilia in the development and disease of the retina. Organogenesis 2014; 10:69-85. [PMID: 24162842 PMCID: PMC4049897 DOI: 10.4161/org.26710] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 10/01/2013] [Accepted: 10/04/2013] [Indexed: 02/07/2023] Open
Abstract
The normal development and function of photoreceptors is essential for eye health and visual acuity in vertebrates. Mutations in genes encoding proteins involved in photoreceptor development and function are associated with a suite of inherited retinal dystrophies, often as part of complex multi-organ syndromic conditions. In this review, we focus on the role of the photoreceptor outer segment, a highly modified and specialized primary cilium, in retinal health and disease. We discuss the many defects in the structure and function of the photoreceptor primary cilium that can cause a class of inherited conditions known as ciliopathies, often characterized by retinal dystrophy and degeneration, and highlight the recent insights into disease mechanisms.
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Affiliation(s)
- Gabrielle Wheway
- Section of Ophthalmology and Neurosciences; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
| | - David A Parry
- Section of Genetics; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
| | - Colin A Johnson
- Section of Ophthalmology and Neurosciences; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
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Miyadera K. Inherited retinal diseases in dogs: advances in gene/mutation discovery. DOBUTSU IDEN IKUSHU KENKYU = JOURNAL OF ANIMAL GENETICS 2014; 42:79-89. [PMID: 26120276 PMCID: PMC4480793 DOI: 10.5924/abgri.42.79] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
1. Inherited retinal diseases (RDs) are vision-threatening conditions affecting humans as well as many domestic animals. Through many years of clinical studies of the domestic dog population, a wide array of RDs has been phenotypically characterized. Extensive effort to map the causative gene and to identify the underlying mutation followed. Through candidate gene, linkage analysis, genome-wide association studies, and more recently, by means of next-generation sequencing, as many as 31 mutations in 24 genes have been identified as the underlying cause for canine RDs. Most of these genes have been associated with human RDs providing opportunities to study their roles in the disease pathogenesis and in normal visual function. The canine model has also contributed in developing new treatments such as gene therapy which has been clinically applied to human patients. Meanwhile, with increasing knowledge of the molecular architecture of RDs in different subpopulations of dogs, the conventional understanding of RDs as a simple monogenic disease is beginning to change. Emerging evidence of modifiers that alters the disease outcome is complicating the interpretation of DNA tests. In this review, advances in the gene/mutation discovery approaches and the emerging genetic complexity of canine RDs are discussed.
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Affiliation(s)
- Keiko Miyadera
- School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey St, Philadelphia PA 19104 USA
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Breed-specific hematological phenotypes in the dog: a natural resource for the genetic dissection of hematological parameters in a mammalian species. PLoS One 2013; 8:e81288. [PMID: 24282579 PMCID: PMC3840015 DOI: 10.1371/journal.pone.0081288] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 10/20/2013] [Indexed: 11/19/2022] Open
Abstract
Remarkably little has been published on hematological phenotypes of the domestic dog, the most polymorphic species on the planet. Information on the signalment and complete blood cell count of all dogs with normal red and white blood cell parameters judged by existing reference intervals was extracted from a veterinary database. Normal hematological profiles were available for 6046 dogs, 5447 of which also had machine platelet concentrations within the reference interval. Seventy-five pure breeds plus a mixed breed control group were represented by 10 or more dogs. All measured parameters except mean corpuscular hemoglobin concentration (MCHC) varied with age. Concentrations of white blood cells (WBCs), neutrophils, monocytes, lymphocytes, eosinophils and platelets, but not red blood cell parameters, all varied with sex. Neutering status had an impact on hemoglobin concentration, mean corpuscular hemoglobin (MCH), MCHC, and concentrations of WBCs, neutrophils, monocytes, lymphocytes and platelets. Principal component analysis of hematological data revealed 37 pure breeds with distinctive phenotypes. Furthermore, all hematological parameters except MCHC showed significant differences between specific individual breeds and the mixed breed group. Twenty-nine breeds had distinctive phenotypes when assessed in this way, of which 19 had already been identified by principal component analysis. Tentative breed-specific reference intervals were generated for breeds with a distinctive phenotype identified by comparative analysis. This study represents the first large-scale analysis of hematological phenotypes in the dog and underlines the important potential of this species in the elucidation of genetic determinants of hematological traits, triangulating phenotype, breed and genetic predisposition.
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Downs LM, Hitti R, Pregnolato S, Mellersh CS. Genetic screening for PRA-associated mutations in multiple dog breeds shows that PRA is heterogeneous within and between breeds. Vet Ophthalmol 2013; 17:126-30. [DOI: 10.1111/vop.12122] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Louise M. Downs
- Kennel Club Genetics Centre; Animal Health Trust; Lanwades Park Newmarket CB8 7UU UK
| | - Rebekkah Hitti
- Kennel Club Genetics Centre; Animal Health Trust; Lanwades Park Newmarket CB8 7UU UK
| | - Silvia Pregnolato
- Kennel Club Genetics Centre; Animal Health Trust; Lanwades Park Newmarket CB8 7UU UK
| | - Cathryn S. Mellersh
- Kennel Club Genetics Centre; Animal Health Trust; Lanwades Park Newmarket CB8 7UU UK
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A CNGB1 frameshift mutation in Papillon and Phalène dogs with progressive retinal atrophy. PLoS One 2013; 8:e72122. [PMID: 24015210 PMCID: PMC3756049 DOI: 10.1371/journal.pone.0072122] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/10/2013] [Indexed: 11/19/2022] Open
Abstract
Progressive retinal degenerations are the most common causes of complete blindness both in human and in dogs. Canine progressive retinal atrophy (PRA) or degeneration resembles human retinitis pigmentosa (RP) and is characterized by a progressive loss of rod photoreceptor cells followed by a loss of cone function. The primary clinical signs are detected as vision impairment in a dim light. Although several genes have been associated with PRAs, there are still PRAs of unknown genetic cause in many breeds, including Papillons and Phalènes. We have performed a genome wide association and linkage studies in cohort of 6 affected Papillons and Phalènes and 14 healthy control dogs to map a novel PRA locus on canine chromosome 2, with a 1.9 Mb shared homozygous region in the affected dogs. Parallel exome sequencing of a trio identified an indel mutation, including a 1-bp deletion, followed by a 6-bp insertion in the CNGB1 gene. This mutation causes a frameshift and premature stop codon leading to probable nonsense mediated decay (NMD) of the CNGB1 mRNA. The mutation segregated with the disease and was confirmed in a larger cohort of 145 Papillons and Phalènes (PFisher = 1.4×10−8) with a carrier frequency of 17.2 %. This breed specific mutation was not present in 334 healthy dogs from 10 other breeds or 121 PRA affected dogs from 44 other breeds. CNGB1 is important for the photoreceptor cell function its defects have been previously associated with retinal degeneration in both human and mouse. Our study indicates that a frameshift mutation in CNGB1 is a cause of PRA in Papillons and Phalènes and establishes the breed as a large functional animal model for further characterization of retinal CNGB1 biology and possible retinal gene therapy trials. This study enables also the development of a genetic test for breeding purposes.
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Winkler PA, Ekenstedt KJ, Occelli LM, Frattaroli AV, Bartoe JT, Venta PJ, Petersen-Jones SM. A large animal model for CNGB1 autosomal recessive retinitis pigmentosa. PLoS One 2013; 8:e72229. [PMID: 23977260 PMCID: PMC3747135 DOI: 10.1371/journal.pone.0072229] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 07/08/2013] [Indexed: 11/25/2022] Open
Abstract
Retinal dystrophies in dogs are invaluable models of human disease. Progressive retinal atrophy (PRA) is the canine equivalent of retinitis pigmentosa (RP). Similar to RP, PRA is a genetically heterogenous condition. We investigated PRA in the Papillon breed of dog using homozygosity mapping and haplotype construction of single nucleotide polymorphisms within a small family group to identify potential positional candidate genes. Based on the phenotypic similarities between the PRA-affected Papillons, mouse models and human patients, CNGB1 was selected as the most promising positional candidate gene. CNGB1 was sequenced and a complex mutation consisting of the combination of a one basepair deletion and a 6 basepair insertion was identified in exon 26 (c.2387delA;2389_2390insAGCTAC) leading to a frameshift and premature stop codon. Immunohistochemistry (IHC) of pre-degenerate retinal sections from a young affected dog showed absence of labeling using a C-terminal CNGB1 antibody. Whereas an antibody directed against the N-terminus of the protein, which also recognizes the glutamic acid rich proteins arising from alternative splicing of the CNGB1 transcript (upstream of the premature stop codon), labeled rod outer segments. CNGB1 combines with CNGA1 to form the rod cyclic nucleotide gated channel and previous studies have shown the requirement of CNGB1 for normal targeting of CNGA1 to the rod outer segment. In keeping with these previous observations, IHC showed a lack of detectable CNGA1 protein in the rod outer segments of the affected dog. A population study did not identify the CNGB1 mutation in PRA-affected dogs in other breeds and documented that the CNGB1 mutation accounts for ∼70% of cases of Papillon PRA in our PRA-affected canine DNA bank. CNGB1 mutations are one cause of autosomal recessive RP making the CNGB1 mutant dog a valuable large animal model of the condition.
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Affiliation(s)
- Paige A. Winkler
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
- Genetics Program, Michigan State University, East Lansing, Michigan, United States of America
| | - Kari J. Ekenstedt
- Department of Animal and Food Sciences, University of Wisconsin-River Falls, River Falls, Wisconsin, United States of America
| | - Laurence M. Occelli
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Anton V. Frattaroli
- Health Information Technology, Michigan State University, East Lansing, Michigan, United States of America
| | - Joshua T. Bartoe
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Patrick J. Venta
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
- Genetics Program, Michigan State University, East Lansing, Michigan, United States of America
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
| | - Simon M. Petersen-Jones
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
- Genetics Program, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
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Petersen-Jones SM. Drug and gene therapy of hereditary retinal disease in dog and cat models. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.ddmod.2014.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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