1
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The molecular genetics of human appendicular skeleton. Mol Genet Genomics 2022; 297:1195-1214. [PMID: 35907958 DOI: 10.1007/s00438-022-01930-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 07/09/2022] [Indexed: 10/16/2022]
Abstract
Disorders that result from de-arrangement of growth, development and/or differentiation of the appendages (limbs and digit) are collectively called as inherited abnormalities of human appendicular skeleton. The bones of appendicular skeleton have central role in locomotion and movement. The different types of appendicular skeletal abnormalities are well described in the report of "Nosology and Classification of Genetic skeletal disorders: 2019 Revision". In the current article, we intend to present the embryology, developmental pathways, disorders and the molecular genetics of the appendicular skeletal malformations. We mainly focused on the polydactyly, syndactyly, brachydactyly, split-hand-foot malformation and clubfoot disorders. To our knowledge, only nine genes of polydactyly, five genes of split-hand-foot malformation, nine genes for syndactyly, eight genes for brachydactyly and only single gene for clubfoot have been identified to be involved in disease pathophysiology. The current molecular genetic data will help life sciences researchers working on the rare skeletal disorders. Moreover, the aim of present systematic review is to gather the published knowledge on molecular genetics of appendicular skeleton, which would help in genetic counseling and molecular diagnosis.
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2
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Cassim A, Hettiarachchi D, Dissanayake VHW. Genetic determinants of syndactyly: perspectives on pathogenesis and diagnosis. Orphanet J Rare Dis 2022; 17:198. [PMID: 35549993 PMCID: PMC9097448 DOI: 10.1186/s13023-022-02339-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 04/26/2022] [Indexed: 12/04/2022] Open
Abstract
The formation of the digits is a tightly regulated process. During embryogenesis, disturbance of genetic pathways in limb development could result in syndactyly; a common congenital malformation consisting of webbing in adjacent digits. Currently, there is a paucity of knowledge regarding the exact developmental mechanism leading to this condition. The best studied canonical interactions of Wingless‐type–Bone Morphogenic Protein–Fibroblast Growth Factor (WNT–BMP–FGF8), plays a role in the interdigital cell death (ICD) which is thought to be repressed in human syndactyly. Animal studies have displayed other pathways such as the Notch signaling, metalloprotease and non-canonical WNT-Planar cell polarity (PCP), to also contribute to failure of ICD, although less prominence has been given. The current diagnosis is based on a clinical evaluation followed by radiography when indicated, and surgical release of digits at 6 months of age is recommended. This review discusses the interactions repressing ICD in syndactyly, and characterizes genes associated with non-syndromic and selected syndromes involving syndactyly, according to the best studied canonical WNT-BMP-FGF interactions in humans. Additionally, the controversies regarding the current syndactyly classification and the effect of non-coding elements are evaluated, which to our knowledge has not been previously highlighted. The aim of the review is to better understand the developmental process leading to this condition.
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Affiliation(s)
- Afraah Cassim
- Human Genetics Unit, Faculty of Medicine, University of Colombo, 25, Kynsey Road, Colombo, Sri Lanka.
| | - Dineshani Hettiarachchi
- Human Genetics Unit, Faculty of Medicine, University of Colombo, 25, Kynsey Road, Colombo, Sri Lanka
| | - Vajira H W Dissanayake
- Human Genetics Unit, Faculty of Medicine, University of Colombo, 25, Kynsey Road, Colombo, Sri Lanka
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3
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Xu J, Chen X, Teng X, Wang X, Chen H. Complex radial polydactyly in a Chinese family: inclusion of triphalangism, triplication, and syndactyly. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1296. [PMID: 34532433 PMCID: PMC8422142 DOI: 10.21037/atm-21-2773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 08/01/2021] [Indexed: 11/21/2022]
Abstract
Background Few studies have investigated families in which multiple individuals over three or more generations are affected by radial polydactyly and syndactyly. This report describes an extremely rare family in which nine individuals across six generations were affected by complex radial polydactyly. Methods We investigated a six-generation pedigree with radial polydactyly including triplication, triphalangism, hypoplasia, and symphalangism. There was a total of 34 individuals (including their spouses) in the family and 11 individuals had polydactyly. The average age of the patients ranged from 7 months to 96 years. The characteristic feature of the malformation in these patients was described. Two patients underwent surgical resection for radial supernumerary thumbs. The Bilhout-Cloquet technique and On-top-plasty technique were used to reconstruct the nail and the joints. Results The patients in this family presented with thumb duplication and triphalangism in both hands, including a variety of deformities, such as triplication, triphalangism, hypoplasia, and symphalangism. Syndactyly and ulnar polydactyly were also frequently observed. Two patients who underwent surgical treatment showed good hand and thumb function at the 8- and 2-year post-operative follow-up, respectively. Conclusions The present study reported various mixed phenotypes including triplication, triphalangism, hypoplasia, and symphalangism within the same family which may represent a rare type of polydactyly. Surgical resection of extra digits to achieve mobility of the thumb is the main treatment option for radial polydactyly. Given the ulnar thumb is better developed, the radial thumb is typically resected in patients with radial polydactyly. These reconstructive principles are fit for this Chinese family as well.
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Affiliation(s)
- Jihai Xu
- Hand Surgery Department, Ningbo No. 6 Hospital, Ningbo, China
| | - Xiaokun Chen
- Department of Orthopedic Trauma, Peking University People Hospital, Beijing, China
| | - Xiaofeng Teng
- Hand Surgery Department, Ningbo No. 6 Hospital, Ningbo, China
| | - Xin Wang
- Hand Surgery Department, Ningbo No. 6 Hospital, Ningbo, China
| | - Hong Chen
- Hand Surgery Department, Ningbo No. 6 Hospital, Ningbo, China
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4
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A 300-kb microduplication of 7q36.3 in a patient with triphalangeal thumb-polysyndactyly syndrome combined with congenital heart disease and optic disc coloboma: a case report. BMC Med Genomics 2020; 13:175. [PMID: 33218365 PMCID: PMC7678048 DOI: 10.1186/s12920-020-00821-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 11/09/2020] [Indexed: 12/04/2022] Open
Abstract
Background Triphalangeal thumb-polysyndactyly syndrome (TPT-PS) is a rare well-defined autosomal dominant disorder characterized by long thumbs with three phalanges combined with pre- and postaxial polydactyly/syndactyly of limbs.
By now, the syndrome has been reported in several large families from different ethnic backgrounds, with a high degree of inter- and intrafamilial variability. The genome locus responsible for TPT-PS has been mapped to the 7q36.3 region harboring a long-range sonic hedgehog (SHH) regulatory sequence (ZRS). Both single-nucleotide variants and complete duplications of ZRS were shown to cause TPT-PS and similar limb phenotypes. TPT-PS usually forms as isolated limb pathology not associated with additional malformations, in particular, with cardiovascular abnormalities. Case presentation Here we report on a rare Russian neonatal case of TPT-PS combined with severe congenital heart disease, namely double outlet right ventricle, and microphthalmia with optic disc coloboma. Pedigree analysis revealed TPT-PS of various expressivity in 10 family members throughout five generations, while the cardiac defect and the eye pathology were detected only in the proband. To extend the knowledge on genotype–phenotype spectrum of TPT-PS, the careful clinical and genomic analysis of the family was performed. High-resolution array-based comparative genomic hybridization (array-CGH) revealed a ~ 300 kb microduplication of 7q36.3 locus (arr[GRCh37] 7q36.3(156385810_156684811) × 3) that co-segregated with TPT-PS in the proband and her mother. The duplication encompassed three genes including LMBR1, the intron 5 of which is known to harbor ZRS. Based on whole-exome sequencing data, no additional pathogenic mutations or variants of uncertain clinical significance were found in morbid cardiac genes or genes associated with a microphthalmia/anophthalmia/coloboma spectrum of ocular malformations. Conclusions The results support the previous data, indicating that complete ZRS duplication underlies TPT-PS, and suggest a broader phenotypic impact of the 7q36.3 microduplication. Potential involvement of the 7q36.3 microduplication in the patient’s cardiac and eye malformations is discussed. However, the contribution of some additional genetic/epigenetic factors to the complex patient`s phenotype cannot be excluded entirely. Further comprehensive functional studies are needed to prove the possible involvement of the 7q36.3 locus in congenital heart disease and eye pathology.
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5
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Shi L, Huang H, Jiang Q, Huang R, Fu W, Mao L, Wei X, Cui H, Lin K, Cai L, Yang Y, Wang Y, Wu J. Sub-Exome Target Sequencing in a Family With Syndactyly Type IV Due to a Novel Partial Duplication of the LMBR1 Gene: First Case Report in Fujian Province of China. Front Genet 2020; 11:130. [PMID: 32184803 PMCID: PMC7058806 DOI: 10.3389/fgene.2020.00130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 02/03/2020] [Indexed: 12/30/2022] Open
Abstract
Syndactyly is one of the most frequent hereditary limb malformations with clinical and genetical complexity. Autosomal dominant syndactyly type IV (SD4) is a rare form of syndactyly, caused by heterozygous mutations in a sonic hedgehog (SHH) regulatory element (ZRS) which resides in intron 5 of the LMBR1 gene on chromosome 7q36.3. SD4 is characterized by complete cutaneous syndactyly of the fingers, accompanied by cup-shaped hands due to flexion of the fingers and polydactyly. Here, for the first time, we reported a large Chinese family from Fujian province, manifesting cup-shaped hands consistent with SD4 and intrafamilial heterogeneity in clinical phenotype of tibial and fibulal shortening, triphalangeal thumb-polysyndactyly syndrome (TPTPS). We identified a novel duplication of ∼222 kb covering exons 2–17 of the LMBR1 gene in this family by sub-exome target sequencing. This case expands our new clinical understanding of SD4 phenotype and again confirms the feasibility to detect copy number variation by sub-exome target sequencing.
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Affiliation(s)
- Lijing Shi
- Department of Ultrasound, Quanzhou Women's and Children's Hospital, Quanzhou, China
| | - Hui Huang
- BGI Genomics, BGI-Shenzhen, Shenzhen, China
| | - Qiuxia Jiang
- Department of Ultrasound, Quanzhou Women's and Children's Hospital, Quanzhou, China
| | - Rongsen Huang
- Department of Ultrasound, Quanzhou Women's and Children's Hospital, Quanzhou, China
| | - Wanyu Fu
- Prenatal Diagnosis Center, Quanzhou Women's and Children's Hospital, Quanzhou, China
| | - Liangwei Mao
- BGI-Wuhan Clinical Laboratories, BGI-Shenzhen, Wuhan, China.,State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan, China
| | - Xiaoming Wei
- BGI-Wuhan Clinical Laboratories, BGI-Shenzhen, Wuhan, China
| | | | - Keke Lin
- BGI Genomics, BGI-Shenzhen, Shenzhen, China
| | - Licheng Cai
- BGI-Guangzhou Medical Laboratory, BGI-Shenzhen, Guangzhou, China
| | - You Yang
- BGI-Guangzhou Medical Laboratory, BGI-Shenzhen, Guangzhou, China
| | - Yuanbai Wang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's Hospital, Quanzhou, China
| | - Jing Wu
- BGI Genomics, BGI-Shenzhen, Shenzhen, China
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6
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Potuijt JWP, Galjaard RJH, van der Spek PJ, van Nieuwenhoven CA, Ahituv N, Oberg KC, Hovius SER. A multidisciplinary review of triphalangeal thumb. J Hand Surg Eur Vol 2019; 44:59-68. [PMID: 30318985 PMCID: PMC6297887 DOI: 10.1177/1753193418803521] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Despite being a rare congenital limb anomaly, triphalangeal thumb is a subject of research in various scientific fields, providing new insights in clinical research and evolutionary biology. The findings of triphalangeal thumb can be predictive for other congenital anomalies as part of an underlying syndrome. Furthermore, triphalangeal thumb is still being used as a model in molecular genetics to study gene regulation by long-range regulatory elements. We present a review that summarizes a number of scientifically relevant topics that involve the triphalangeal thumb phenotype. Future initiatives involving multidisciplinary teams collaborating in the field of triphalangeal thumb research can lead to a better understanding of the pathogenesis and molecular mechanisms of this condition as well as other congenital upper limb anomalies.
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Affiliation(s)
- Jacob W. P. Potuijt
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands,Jacob W. P. Potuijt, Department of Plastic, Reconstructive and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, Ee-1589 Postbus 2040, 3015 GE Rotterdam, The Netherlands.
| | - Robert-Jan H. Galjaard
- Department of Clinical Genetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Peter J. van der Spek
- Department of Bioinformatics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands,Department of Pathology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Christianne A. van Nieuwenhoven
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Nadav Ahituv
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, SF, USA,Institute for Human Genetics, University of California San Francisco, SF, USA
| | - Kerby C. Oberg
- Department of Pathology and Human Anatomy, Loma Linda University, Loma Linda, USA
| | - Steven E. R. Hovius
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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7
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Zone of Polarizing Activity Regulatory Sequence Mutations/Duplications with Preaxial Polydactyly and Longitudinal Preaxial Ray Deficiency in the Phenotype: A Review of Human Cases, Animal Models, and Insights Regarding the Pathogenesis. BIOMED RESEARCH INTERNATIONAL 2018; 2018:1573871. [PMID: 29651423 PMCID: PMC5832050 DOI: 10.1155/2018/1573871] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/19/2017] [Accepted: 01/16/2018] [Indexed: 02/06/2023]
Abstract
Clinicians and scientists interested in developmental biology have viewed preaxial polydactyly (PPD) and longitudinal preaxial ray deficiency (LPAD) as two different entities. Point mutations and duplications in the zone of polarizing activity regulatory sequence (ZRS) are associated with anterior ectopic expression of Sonic Hedgehog (SHH) in the limb bud and usually result in a PPD phenotype. However, some of these mutations/duplications also have LPAD in the phenotype. This unusual PPD-LPAD association in ZRS mutations/duplications has not been specifically reviewed in the literature. The author reviews this unusual entity and gives insights regarding its pathogenesis.
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8
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Wang B, Diao Y, Liu Q, An H, Ma R, Jiang G, Lai N, Li Z, Zhu X, Zhao L, Guo Q, Zhang Z, Sun R, Li X. An increased duplication of ZRS region that caused more than one supernumerary digits preaxial polydactyly in a large Chinese family. Sci Rep 2016; 6:38500. [PMID: 27922091 PMCID: PMC5138840 DOI: 10.1038/srep38500] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 11/10/2016] [Indexed: 01/30/2023] Open
Abstract
Preaxial polydactyly (PPD) is inherited in an autosomal dominant fashion and characterized by the presence of one or more supernumerary digits on the thumb side. It had been identified that point mutation or genomic duplications of the long-range limb-specific cis-regulator - zone of polarizing activity regulatory sequence (ZRS) cause PPD or other limb deformities such as syndactyly type IV (SD4) and Triphalangeal thumb-polysyndactyly syndrome (TPTPS). Most previously reported cases involved with no more than one extra finger; however, the role of the point mutation or genomic duplications of ZRS in the case of more than one redundant finger polydactyly remains unclear. In this article, we reported a family case of more than one redundant finger polydactyly on the thumb side for bilateral hands with a pedigree chart of the family. Results of quantitative PCR (qPCR) and sequence analysis suggested that the relative copy number (RCN) of ZRS but not point mutation (including insertion and deletion) was involved in all affected individuals.
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Affiliation(s)
- Bin Wang
- Department of peripheral vascular disease, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, 42 Wenhua xi Road, Jinan 250011, Shandong, China
| | - Yutao Diao
- Key Laboratory for Rare &Uncommon diseases of Shandong province, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan 250062, Shandong, China
| | - Qiji Liu
- Department of medical genetics, Shandong University, School of Medicine, Jinan 250012, Shandong, China
| | - Hongqiang An
- Department of Orthopedic Surgery, People's Hospital of Xintai, Xintai 271200, Shandong, China
| | - Ruiping Ma
- Shandong Provincial Qianfoshan Hospital, 16766 Jingshi Road, Jinan 250014, Shandong, China
| | - Guosheng Jiang
- Key Laboratory for Rare &Uncommon diseases of Shandong province, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan 250062, Shandong, China
| | - Nannan Lai
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Ziwei Li
- Key Laboratory for Rare &Uncommon diseases of Shandong province, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan 250062, Shandong, China
| | - Xiaoxiao Zhu
- Key Laboratory for Rare &Uncommon diseases of Shandong province, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan 250062, Shandong, China
| | - Lin Zhao
- Key Laboratory for Rare &Uncommon diseases of Shandong province, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan 250062, Shandong, China
| | - Qiang Guo
- Key Laboratory for Rare &Uncommon diseases of Shandong province, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan 250062, Shandong, China
| | - Zhen Zhang
- Key Laboratory for Rare &Uncommon diseases of Shandong province, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan 250062, Shandong, China
| | - Rong Sun
- Shandong Academy of Chinese Medicine, Yanzi Shanxi Road, Jinan 250014, Shandong, China
| | - Xia Li
- Key Laboratory for Rare &Uncommon diseases of Shandong province, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan 250062, Shandong, China
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9
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Abstract
Polydactyly is one of the most common inherited limb abnormalities, characterised by supernumerary fingers or toes. It results from disturbances in the normal programme of the anterior-posterior axis of the developing limb, with diverse aetiology and variable inter- and intra-familial clinical features. Polydactyly can occur as an isolated disorder (non-syndromic polydactyly) or as a part of an anomaly syndrome (syndromic polydactyly). On the basis of the anatomic location of the duplicated digits, non-syndromic polydactyly is divided into three kinds, including preaxial polydactyly, axial polydactyly and postaxial polydactyly. Non-syndromic polydactyly frequently exhibits an autosomal dominant inheritance with variable penetrance. To date, in human, at least ten loci and four disease-causing genes, including the GLI3 gene, the ZNF141 gene, the MIPOL1 gene and the PITX1 gene, have been identified. In this paper, we review clinical features of non-syndromic polydactyly and summarise the recent progress in the molecular genetics, including loci and genes that are responsible for the disorder, the signalling pathways that these genetic factors are involved in, as well as animal models of the disorder. These progresses will improve our understanding of the complex disorder and have implications on genetic counselling such as prenatal diagnosis.
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10
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Deng H, Tan T. Advances in the Molecular Genetics of Non-syndromic Syndactyly. Curr Genomics 2015; 16:183-93. [PMID: 26069458 PMCID: PMC4460222 DOI: 10.2174/1389202916666150317233103] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/18/2015] [Accepted: 03/16/2015] [Indexed: 12/16/2022] Open
Abstract
Syndactyly, webbing of adjacent digits with or without bony fusion, is one of the most common hereditary limb malformations. It occurs either as an isolated abnormality or as a component of more than 300 syndromic anomalies. There are currently nine types of phenotypically diverse nonsyndromic syndactyly. Non-syndromic syndactyly is usually inherited as an autosomal dominant trait, although the more severe presenting types and subtypes may show autosomal recessive or X-linked pattern of inheritance. The phenotype appears to be not only caused by a main gene, but also dependant on genetic background and subsequent signaling pathways involved in limb formation. So far, the principal genes identified to be involved in congenital syndactyly are mainly involved in the zone of polarizing activity and sonic hedgehog pathway. This review summarizes the recent progress made in the molecular genetics, including known genes and loci responsible for non-syndromic syndactyly, and the signaling pathways those genetic factors involved in, as well as clinical features and animal models. We hope our review will contribute to the understanding of underlying pathogenesis of this complicated disorder and have implication on genetic counseling.
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Affiliation(s)
- Hao Deng
- Center for Experimental Medicine ; Department of Neurology, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Ting Tan
- Center for Experimental Medicine
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11
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Vanlerberghe C, Faivre L, Petit F, Fruchart O, Jourdain AS, Clavier F, Gay S, Manouvrier-Hanu S, Escande F. Intrafamilial variability of ZRS-associated syndrome: characterization of a mosaic ZRS mutation by pyrosequencing. Clin Genet 2015; 88:479-83. [PMID: 25382487 DOI: 10.1111/cge.12534] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 10/29/2014] [Accepted: 11/03/2014] [Indexed: 12/13/2022]
Abstract
During limb development, the spatio-temporal expression of sonic hedgehog (SHH) is driven by the Zone of polarizing activity Regulatory Sequence (ZRS), located 1 megabase upstream from SHH. Gain-of-function mutations of this enhancer, which cause ectopic expression of SHH, are known to be responsible for congenital limb malformations with variable expressivity, ranging from preaxial polydactyly or triphalangeal thumbs to polysyndactyly, which may also be associated with mesomelic deficiency. In this report, we describe a patient affected with mirror-image polydactyly of the four extremities and bilateral tibial deficiency. The proband's father had isolated preaxial polydactyly type II (PPD2). Using Sanger sequencing, a ZRS point mutation (NC_000007.14, g.156584153A>G, UCSC, Build hg.19) was only identified in the patient. However, pyrosequencing analysis enabled the detection of a 10% somatic mosaic in the blood and saliva from the father. To our knowledge, this is the first description of a ZRS mosaic mutation. This report highlights the complexity of genotype-phenotype correlation in ZRS-associated syndromes and the importance of detecting somatic mosaicism for accurate genetic counselling.
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Affiliation(s)
- C Vanlerberghe
- Institut de Biochimie et Génétique Moléculaire, Centre de Biologie Pathologie, CHRU, Lille, France.,Clinique de Génétique médicale, Hôpital Jeanne de Flandre, CHRU, Lille, France.,RADEME Research Team for Rare Metabolic and Developmental Diseases, Université Lille 2, Lille, France
| | - L Faivre
- Service de Génétique clinique, Hôpital d'enfants, Dijon, France
| | - F Petit
- Clinique de Génétique médicale, Hôpital Jeanne de Flandre, CHRU, Lille, France.,RADEME Research Team for Rare Metabolic and Developmental Diseases, Université Lille 2, Lille, France.,Faculté de Médecine, Université Lille II, Lille, France
| | - O Fruchart
- Institut de Biochimie et Génétique Moléculaire, Centre de Biologie Pathologie, CHRU, Lille, France.,RADEME Research Team for Rare Metabolic and Developmental Diseases, Université Lille 2, Lille, France
| | - A-S Jourdain
- Institut de Biochimie et Génétique Moléculaire, Centre de Biologie Pathologie, CHRU, Lille, France.,RADEME Research Team for Rare Metabolic and Developmental Diseases, Université Lille 2, Lille, France
| | - F Clavier
- Centre de référence national maladies rares des malformations des membres et de l'arthrogrypose chez l'enfant Saint Maurice, Hôpital Saint Maurice, Saint Maurice, France
| | - S Gay
- Service de pédiatrie, Centre Hospitalier William Morey, Chalon sur Saône, France
| | - S Manouvrier-Hanu
- Clinique de Génétique médicale, Hôpital Jeanne de Flandre, CHRU, Lille, France.,RADEME Research Team for Rare Metabolic and Developmental Diseases, Université Lille 2, Lille, France.,Faculté de Médecine, Université Lille II, Lille, France
| | - F Escande
- Institut de Biochimie et Génétique Moléculaire, Centre de Biologie Pathologie, CHRU, Lille, France.,RADEME Research Team for Rare Metabolic and Developmental Diseases, Université Lille 2, Lille, France
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12
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Lohan S, Spielmann M, Doelken SC, Flöttmann R, Muhammad F, Baig SM, Wajid M, Hülsemann W, Habenicht R, Kjaer KW, Patil SJ, Girisha KM, Abarca-Barriga HH, Mundlos S, Klopocki E. Microduplications encompassing the Sonic hedgehog limb enhancer ZRS are associated with Haas-type polysyndactyly and Laurin-Sandrow syndrome. Clin Genet 2014; 86:318-25. [PMID: 24456159 DOI: 10.1111/cge.12352] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/16/2014] [Accepted: 01/20/2014] [Indexed: 12/17/2022]
Abstract
Laurin-Sandrow syndrome (LSS) is a rare autosomal dominant disorder characterized by polysyndactyly of hands and/or feet, mirror image duplication of the feet, nasal defects, and loss of identity between fibula and tibia. The genetic basis of LSS is currently unknown. LSS shows phenotypic overlap with Haas-type polysyndactyly (HTS) regarding the digital phenotype. Here we report on five unrelated families with overlapping microduplications encompassing the Sonic hedgehog (SHH) limb enhancer ZPA regulatory sequence (ZRS) on chromosome 7q36. Clinically, the patients show polysyndactyly phenotypes and various types of lower limb malformations ranging from syndactyly to mirror image polydactyly with duplications of the fibulae. We show that larger duplications of the ZRS region (>80 kb) are associated with HTS, whereas smaller duplications (<80 kb) result in the LSS phenotype. On the basis of our data, the latter can be clearly distinguished from HTS by the presence of mirror image polysyndactyly of the feet with duplication of the fibula. Our results expand the clinical phenotype of the ZRS-associated syndromes and suggest that smaller duplications (<80 kb) are associated with a more severe phenotype. In addition, we show that these small microduplications within the ZRS region are the underlying genetic cause of Laurin-Sandrow syndrome.
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Affiliation(s)
- S Lohan
- Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin Berlin, Berlin, Germany; Max Planck Institute for Molecular Genetics, Research Group Mundlos, Berlin, Germany
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13
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Girisha KM, Bidchol AM, Kamath PS, Shah KH, Mortier GR, Mundlos S, Shah H. A novel mutation (g.106737G>T) in zone of polarizing activity regulatory sequence (ZRS) causes variable limb phenotypes in Werner mesomelia. Am J Med Genet A 2014; 164A:898-906. [PMID: 24478176 DOI: 10.1002/ajmg.a.36367] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 10/22/2013] [Indexed: 12/12/2022]
Abstract
Werner mesomelia is characterized by a sequence variation in the specific region (position 404) of the enhancer ZRS of SHH. The phenotype comprises variable mesomelia, abnormalities of the thumb and great toe and supernumerary digits. We describe extensive variation in limb phenotype in a large family and report on a novel sequence variation NG_009240.1: g.106737G>T (traditional nomenclature: ZRS404G>T) in the ZRS within the LMBR1 gene. The newly recognized clinical features in this family include small thenar eminence, sandal gap, broad first metatarsals, mesoaxial polydactyly, and postaxial polydactyly. We provide information on 12 affected family members. We review the literature on how a sequence variation in ZRS may cause such diverse phenotypes.
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Affiliation(s)
- Katta M Girisha
- Division of Medical Genetics, Department of Pediatrics, Kasturba Medical College, Manipal University, Manipal, India
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14
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Hox5 interacts with Plzf to restrict Shh expression in the developing forelimb. Proc Natl Acad Sci U S A 2013; 110:19438-43. [PMID: 24218595 DOI: 10.1073/pnas.1315075110] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
To date, only the five most posterior groups of Hox genes, Hox9-Hox13, have demonstrated loss-of-function roles in limb patterning. Individual paralog groups control proximodistal patterning of the limb skeletal elements. Hox9 genes also initiate the onset of Hand2 expression in the posterior forelimb compartment, and collectively, the posterior HoxA/D genes maintain posterior Sonic Hedgehog (Shh) expression. Here we show that an anterior Hox paralog group, Hox5, is required for forelimb anterior patterning. Deletion of all three Hox5 genes (Hoxa5, Hoxb5, and Hoxc5) leads to anterior forelimb defects resulting from derepression of Shh expression. The phenotype requires the loss of all three Hox5 genes, demonstrating the high level of redundancy in this Hox paralogous group. Further analyses reveal that Hox5 interacts with promyelocytic leukemia zinc finger biochemically and genetically to restrict Shh expression. These findings, along with previous reports showing that point mutations in the Shh limb enhancer lead to similar anterior limb defects, highlight the importance of Shh repression for proper patterning of the vertebrate limb.
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15
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Dai L, Guo H, Meng H, Zhang K, Hu H, Yao H, Bai Y. Confirmation of genetic homogeneity of syndactyly type IV and triphalangeal thumb-polysyndactyly syndrome in a Chinese family and review of the literature. Eur J Pediatr 2013; 172:1467-73. [PMID: 23793141 DOI: 10.1007/s00431-013-2071-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 06/09/2013] [Indexed: 12/11/2022]
Abstract
UNLABELLED Syndactyly type IV (SD4) is inherited in an autosomal dominant fashion and characterized by complete cutaneous syndactyly of all fingers accompanied with polydactyly. Triphalangeal thumb-polysyndactyly syndrome (TPTPS) consists of a triphalangeal thumb, polydactyly, and syndactyly and is transmitted in an autosomal dominant manner with variable expression. Genomic duplications of the long-range limb-specific cis-regulator (ZRS) cause SD4 and TPTPS. Here, we report two individuals from a Chinese family with syndactyly. One individual had overlapping clinical symptoms of TPTPS and SD4, while the other had a typical SD4 with postaxial polydactyly of the toe. Results of quantitative PCR suggested that the duplication of ZRS involved all affected individuals, and array comparative genomic hybridization detected its size as 115.3 kb. CONCLUSION This work confirms the genetic homogeneity of SD4 and TPTPS. Our result expands the spectrum of ZRS duplications. TPTPS and SD4 should be considered as a continuum of phenotypes.
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Affiliation(s)
- Limeng Dai
- Department of Medical Genetics, College of Basic Medical Science, Third Military Medical University, Chongqing, 400038, China
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16
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Al-Qattan MM, Shamseldin HE, Al Mazyad M, Al Deghaither S, Alkuraya FS. Genetic heterogeneity in type III familial cutaneous syndactyly and linkage to chromosome 7q36. Am J Med Genet A 2013; 161A:1579-84. [DOI: 10.1002/ajmg.a.35956] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 03/08/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Mohammad M. Al-Qattan
- Department of Surgery; College of Medicine, King Saud University; Riyadh; Saudi Arabia
| | - Hanan E. Shamseldin
- Department of Genetics; King Faisal Specialist Hospital and Research Center; Riyadh; Saudi Arabia
| | - Mohammed Al Mazyad
- Department of Surgery; College of Medicine, King Saud University; Riyadh; Saudi Arabia
| | - Saud Al Deghaither
- Department of Surgery; College of Medicine, King Saud University; Riyadh; Saudi Arabia
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17
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Spielmann M, Mundlos S. Structural variations, the regulatory landscape of the genome and their alteration in human disease. Bioessays 2013; 35:533-43. [PMID: 23625790 DOI: 10.1002/bies.201200178] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
High-throughput genomic technologies are revolutionizing human genetics. So far the focus has been on the 1.5% of the genome, which is coding, in spite of the fact that the great majority of genomic variants fall outside the coding regions. Recent efforts to annotate the non-coding sequence show that over 80% of the genome is biochemically active. The genome is divided into regulatory domains consisting of sequence regions that enhance and/or silence the expression of nearby genes and are, in some cases, separated by boundaries with insulator activity. In this paper, we review the recent advances in the identification of variations that influence gene regulation and their consequences for human disease. We hypothesize that structural variations outside of the coding genome can interfere with normal gene regulation by disrupting the regulatory landscape. Therefore, the regulatory landscape of the genome has also to be taken into consideration when investigating the pathology of human disease.
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Affiliation(s)
- Malte Spielmann
- Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, Berlin, Germany
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18
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Spielmann M, Klopocki E. CNVs of noncoding cis-regulatory elements in human disease. Curr Opin Genet Dev 2013; 23:249-56. [PMID: 23601627 DOI: 10.1016/j.gde.2013.02.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 02/08/2013] [Accepted: 02/25/2013] [Indexed: 12/22/2022]
Abstract
Genomic rearrangements and copy-number variations (CNVs) are structural aberrations of the human genome which contribute to phenotypic variation as well as human disease. By now it is well accepted that structural aberrations affecting coding regions can have pathogenic effects, however, noncoding variants have only recently come into focus as disease-associated variants. The phenotypes associated with alterations in noncoding regions with regulatory potential can be striking and at the same time confined to a certain tissue/organ. Future studies will elucidate the frequency of these changes which are expected to be higher among conditions that are due to disturbance of complex developmental processes. Integrating these data with the recently published data from the ENCODE project will broaden our view of genes and their regulation and contribute to our understanding of pathomechanism underlying human disease. In this article, we review the recent advances in the identification of genomic rearrangements and CNVs in noncoding regions of the genome and their consequences for human disease.
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Affiliation(s)
- Malte Spielmann
- Institute for Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany
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19
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Al-Qattan MM, Al Abdulkareem I, Al Haidan Y, Al Balwi M. A novel mutation in the SHH long-range regulator (ZRS) is associated with preaxial polydactyly, triphalangeal thumb, and severe radial ray deficiency. Am J Med Genet A 2012; 158A:2610-5. [PMID: 22903933 DOI: 10.1002/ajmg.a.35584] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 07/02/2012] [Indexed: 12/12/2022]
Abstract
Sonic Hedgehog (SHH) within the posteriorly located zone of polarizing activity is the main controller of the antero-posterior axis of limb development. The ZRS (zone of polarizing activity regulatory sequence) is a long-range limb-specific SHH enhancer. Several point mutations in the ZRS have been described in humans. These mutations cause enhanced SHH activity and ectopic anterior expression of SHH and a variable phenotype of preaxial polydactyly and triphalangeal thumb. Absent thumb or radius has not been reported with ZRS mutations. Here, we report on a family with a variable phenotype of preaxial polydactyly as well as absent thumb and radius, with kidney and cardiac defects. The family was screened for SALL1, SALL4, and TBX5 mutations, but all were normal. Finally, they were screened for ZRS mutations, which showed a novel point mutation within the ZRS, NG_009240.1: g.106954C>T (traditional nomenclature: ZRS619C>T) in the five affected members. This mutation was not previously reported in any public domain database, and was not found in our healthy and ethnically matched control individuals or unaffected family members. We hypothesize that interactions of SHH and SALL1 explain the overlapping features of the family described here and patients with Townes-Brocks syndrome.
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20
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Malik S. Syndactyly: phenotypes, genetics and current classification. Eur J Hum Genet 2012; 20:817-24. [PMID: 22333904 PMCID: PMC3400728 DOI: 10.1038/ejhg.2012.14] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 01/03/2012] [Accepted: 01/06/2012] [Indexed: 01/08/2023] Open
Abstract
Syndactyly is one of the most common hereditary limb malformations depicting the fusion of certain fingers and/or toes. It may occur as an isolated entity or a component of more than 300 syndromic anomalies. Syndactylies exhibit great inter- and intra-familial clinical variability. Even within a subject, phenotype can be unilateral or bilateral and symmetrical or asymmetrical. At least nine non-syndromic syndactylies with additional sub-types have been characterized. Most of the syndactyly types are inherited as autosomal dominant but two autosomal recessive and an X-linked recessive entity have also been described. Whereas the underlying genes/mutations for types II-1, III, IV, V, and VII have been worked out, the etiology and molecular basis of the other syndactyly types remain unknown. In this communication, based on an overview of well-characterized isolated syndactylies, their cardinal phenotypes, inheritance patterns, and clinical and genetic heterogeneities, a 'current classification scheme' is presented. Despite considerable progress in the understanding of syndactyly at clinical and molecular levels, fundamental questions regarding the disturbed developmental mechanisms leading to fused digits, remain to be answered.
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Affiliation(s)
- Sajid Malik
- Human Genetics Program, Department of Animal Sciences, Quaid-i-Azam University Islamabad, Islamabad, Pakistan.
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21
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Klopocki E, Mundlos S. Copy-number variations, noncoding sequences, and human phenotypes. Annu Rev Genomics Hum Genet 2011; 12:53-72. [PMID: 21756107 DOI: 10.1146/annurev-genom-082410-101404] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Whereas single-nucleotide polymorphisms and their role in predisposition to disease have been studied extensively, the analysis of structural variants--genomic changes such as insertions, deletions, inversions, duplications, and translocations--is still in its infancy. Changes in copy number, also known as copy-number variations (CNVs), constitute one such group of these structural variants. CNVs are structural genomic variants that arise from deletions (loss) or duplications (gain), and as a consequence result in a copy-number change of the respective genomic region. CNVs may include entire genes or regions of transcribed sequence, or, indeed, comprise only nontranscribed sequences. Whereas the duplication or deletion of a gene can be expected to have an effect on gene dosage, the consequences of CNVs in nontranscribed sequences are less obvious. Here we review CNVs that involve regulatory nontranscribed regions of the genome, describe the associated human phenotypes, and discuss possible disease mechanisms.
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Affiliation(s)
- Eva Klopocki
- Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany.
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22
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Albuisson J, Isidor B, Giraud M, Pichon O, Marsaud T, David A, Le Caignec C, Bezieau S. Identification of two novel mutations in Shh long-range regulator associated with familial pre-axial polydactyly. Clin Genet 2011; 79:371-7. [PMID: 20569257 DOI: 10.1111/j.1399-0004.2010.01465.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Pre-axial polydactyly type II (PPDII, MIM #174500), Werner mesomelic syndrome (MIM %188770) and Haas polysyndactyly (MIM #186200) are a group of closely related conditions caused by mutations in a long-range Sonic hedgehog (SHH, MIM *600725) regulator called ZRS. To date, 19 point mutations, 10 duplications and 1 triplication of the ZRS associated with those pre-axial polydactylies have been reported in humans, mice, cats and chickens. Some of these have been shown to cause ectopic expression of Shh in the limb bud in mice, leading to a polydactylous phenotype, but the precise mechanism by which ZRS mutations generate this phenotype remains unknown. We present two PPDII families with fully penetrant point mutations in ultra-conserved predicted binding sites for transcription factors SOX9 and PAX3, two possible candidates for regulating SHH expression. Screening for point mutations or copy-number variation of the ZRS, high-resolution array-CGH, and screening of other conserved non-coding sequences (CNS) surrounding SHH in a third family are negative. This is the sixth PPDII pedigree with possible linkage to 7q36 that presents with no detectable ZRS mutation. We hypothesize that another nearby regulatory sequence, or an undetected position effect between ZRS and SHH, could be responsible for negative familial cases linked to 7q36.
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Affiliation(s)
- J Albuisson
- CHU Nantes, Service de Génétique Médicale, 9 quai Moncousu, Nantes Cedex 01, France
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23
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VanderMeer JE, Ahituv N. cis-regulatory mutations are a genetic cause of human limb malformations. Dev Dyn 2011; 240:920-30. [PMID: 21509892 DOI: 10.1002/dvdy.22535] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2010] [Indexed: 01/04/2023] Open
Abstract
The underlying mutations that cause human limb malformations are often difficult to determine, particularly for limb malformations that occur as isolated traits. Evidence from a variety of studies shows that cis-regulatory mutations, specifically in enhancers, can lead to some of these isolated limb malformations. Here, we provide a review of human limb malformations that have been shown to be caused by enhancer mutations and propose that cis-regulatory mutations will continue to be identified as the cause of additional human malformations as our understanding of regulatory sequences improves.
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Affiliation(s)
- Julia E VanderMeer
- Department of Bioengineering and Therapeutic Sciences, and Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
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24
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Baldridge D, Shchelochkov O, Kelley, B, Lee B. Signaling Pathways in Human Skeletal Dysplasias. Annu Rev Genomics Hum Genet 2010; 11:189-217. [DOI: 10.1146/annurev-genom-082908-150158] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Dustin Baldridge
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030; , , ,
| | - Oleg Shchelochkov
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030; , , ,
- Department of Pediatrics, Division of Genetics, University of Iowa, Iowa City, Iowa 52242
| | - Brian Kelley,
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030; , , ,
- Howard Hughes Medical Institute, Houston, Texas 77009
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030; , , ,
- Howard Hughes Medical Institute, Houston, Texas 77009
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25
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Wieczorek D, Pawlik B, Li Y, Akarsu NA, Caliebe A, May KJW, Schweiger B, Vargas FR, Balci S, Gillessen-Kaesbach G, Wollnik B. A specific mutation in the distant sonic hedgehog (SHH) cis-regulator (ZRS) causes Werner mesomelic syndrome (WMS) while complete ZRS duplications underlie Haas type polysyndactyly and preaxial polydactyly (PPD) with or without triphalangeal thumb. Hum Mutat 2010; 31:81-9. [PMID: 19847792 DOI: 10.1002/humu.21142] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Werner mesomelic syndrome (WMS) is an autosomal dominant disorder with unknown molecular etiology characterized by hypo- or aplasia of the tibiae in addition to the preaxial polydactyly (PPD) of the hands and feet and/or five-fingered hand with absence of thumbs. We show that point mutations of a specific nucleotide within the sonic hedgehog (SHH) regulatory region (ZRS) cause WMS. In a previously unpublished WMS family, we identified the causative G>A transition at position 404 of the ZRS, and in six affected family members of a second WMS family we found a 404G>C mutation of the ZRS. The 404G>A ZRS mutation is known as the "Cuban mutation" of PPD type II (PPD2). Interestingly, the index patient of that family had tibial hypoplasia as well. These data provide the first evidence that WMS is caused by a specific ZRS mutation, which leads to strong ectopic SHH expression. In contrast, we show that complete duplications of the ZRS region lead to type Haas polysyndactyly or triphalangeal thumb-polysyndactyly syndrome, but do not affect lower limb development. We suggest the term "ZRS-associated syndromes" and a clinical subclassification for the continuum of limb malformations caused by different molecular alterations of the ZRS.
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Affiliation(s)
- Dagmar Wieczorek
- Institut für Humangenetik, Universitätsklinikum Essen, Hufelandstr. 55, Essen 45122, Germany.
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