1
|
Akbar W, Ullah A, Haider N, Suleman S, Khan FU, Shah AA, Sikandar MA, Basit S, Ahmad W. Identification of novel homozygous variants in FOXE3 and AP4M1 underlying congenital syndromic anophthalmia and microphthalmia. J Gene Med 2024; 26:e3601. [PMID: 37758467 DOI: 10.1002/jgm.3601] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 08/14/2023] [Accepted: 09/13/2023] [Indexed: 10/03/2023] Open
Abstract
BACKGROUND Anophthalmia and microphthalmia are severe developmental ocular disorders that affect the size of the ocular globe and can be unilateral or bilateral. The disease is found in syndromic as well as non-syndromic forms. It is genetically caused by chromosomal aberrations, copy number variations and single gene mutations, along with non-genetic factors such as viral infections, deficiency of vitamin A and an exposure to alcohol or drugs during pregnancy. To date, more than 30 genes having different modes of inheritance patterns are identified as causing anophthalmia and microphthalmia. METHODS In the present study, a clinical and genetic analysis was performed of six patients with anophthalmia and microphthalmia and/or additional phenotypes of intellectual disability, developmental delay and cerebral palsy from a large consanguineous Pakistani family. Whole exome sequencing followed by data analysis for variants prioritization and validation through Sanger sequencing was performed to identify the disease causing variant(s). American College of Medical Genetics and Genomics (ACMG) guidelines were applied to classify clinical interpretation of the prioritized variants. RESULTS Clinical investigations revealed that the affected individuals are afflicted with anophthalmia. Three of the patients showed additional phenotype of intellectual disability, developmental delays and other neurological symptoms. Whole exome sequencing of the DNA samples of the affected members in the family identified a novel homozygous stop gain mutation (NM_012186: c.106G>T: p.Glu36*) in Forkhead Box E3 (FOXE3) gene shared by all affected individuals. Moreover, patients segregating additional phenotypes of spastic paraplegia, intellectual disability, hearing loss and microcephaly showed an additional homozygous sequence variant (NM_004722: c.953G>A: p.Arg318Gln) in AP4M1. Sanger sequencing validated the correct segregation of the identified variants in the affected family. ACMG guidelines predicted the variants to be pathogenic. CONCLUSIONS We have investigated first case of syndromic anophthalmia caused by variants in the FOXE3 and AP4M1. The present findings are helpful for understanding pathological role of the mutations of the genes in syndromic forms of anophthalmia. Furthermore, the study signifies searching for the identification of second variant in families with patients exhibiting variable phenotypes. In addition, the findings will help clinical geneticists, genetic counselors and the affected family with respect to prenatal testing, family planning and genetic counseling.
Collapse
Affiliation(s)
- Warda Akbar
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Asmat Ullah
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Nighat Haider
- Shaheed Zulfiqar Ali Bhutto Medical University, Department of Pediatrics, Pakistan Institute of Medical Sciences, Islamabad, Pakistan
| | - Sufyan Suleman
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Fati Ullah Khan
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Abid Ali Shah
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | | | - Sulman Basit
- College of Medicine, Taibah University, Medina, Saudi Arabia
- Center for Genetics and Inherited Diseases, Taibah University, Medina, Saudi Arabia
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| |
Collapse
|
2
|
Molecular Dynamic Simulation Analysis of a Novel Missense Variant in CYB5R3 Gene in Patients with Methemoglobinemia. MEDICINA (KAUNAS, LITHUANIA) 2023; 59:medicina59020379. [PMID: 36837579 PMCID: PMC9967277 DOI: 10.3390/medicina59020379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 02/18/2023]
Abstract
Background and Objective: Mutations in the CYB5R3 gene cause reduced NADH-dependent cytochrome b5 reductase enzyme function and consequently lead to recessive congenital methemoglobinemia (RCM). RCM exists as RCM type I (RCM1) and RCM type II (RCM2). RCM1 leads to higher methemoglobin levels causing only cyanosis, while in RCM2, neurological complications are also present along with cyanosis. Materials and Methods: In the current study, a consanguineous Pakistani family with three individuals showing clinical manifestations of cyanosis, chest pain radiating to the left arm, dyspnea, orthopnea, and hemoptysis was studied. Following clinical assessment, a search for the causative gene was performed using whole exome sequencing (WES) and Sanger sequencing. Various variant effect prediction tools and ACMG criteria were applied to interpret the pathogenicity of the prioritized variants. Molecular dynamic simulation studies of wild and mutant systems were performed to determine the stability of the mutant CYB5R3 protein. Results: Data analysis of WES revealed a novel homozygous missense variant NM_001171660.2: c.670A > T: NP_001165131.1: p.(Ile224Phe) in exon 8 of the CYB5R3 gene located on chromosome 22q13.2. Sanger sequencing validated the segregation of the identified variant with the disease phenotype within the family. Bioinformatics prediction tools and ACMG guidelines predicted the identified variant p.(Ile224Phe) as disease-causing and likely pathogenic, respectively. Molecular dynamics study revealed that the variant p.(Ile224Phe) in the CYB5R3 resides in the NADH domain of the protein, the aberrant function of which is detrimental. Conclusions: The present study expanded the variant spectrum of the CYB5R3 gene. This will facilitate genetic counselling of the same and other similar families carrying mutations in the CYB5R3 gene.
Collapse
|
3
|
Iyyanar PPR, Wu Z, Lan Y, Hu YC, Jiang R. Alx1 Deficient Mice Recapitulate Craniofacial Phenotype and Reveal Developmental Basis of ALX1-Related Frontonasal Dysplasia. Front Cell Dev Biol 2022; 10:777887. [PMID: 35127681 PMCID: PMC8815032 DOI: 10.3389/fcell.2022.777887] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 01/04/2022] [Indexed: 11/13/2022] Open
Abstract
Loss of ALX1 function causes the frontonasal dysplasia syndrome FND3, characterized by severe facial clefting and microphthalmia. Whereas the laboratory mouse has been the preeminent animal model for studying developmental mechanisms of human craniofacial birth defects, the roles of ALX1 in mouse frontonasal development have not been well characterized because the only previously reported Alx1 mutant mouse line exhibited acrania due to a genetic background-dependent failure of cranial neural tube closure. Using CRISPR/Cas9-mediated genome editing, we have generated an Alx1-deletion mouse model that recapitulates the FND craniofacial malformations, including median orofacial clefting and disruption of development of the eyes and alae nasi. In situ hybridization analysis showed that Alx1 is strongly expressed in frontonasal neural crest cells that give rise to periocular and frontonasal mesenchyme. Alx1del/del embryos exhibited increased apoptosis of periocular mesenchyme and decreased expression of ocular developmental regulators Pitx2 and Lmxb1 in the periocular mesenchyme, followed by defective optic stalk morphogenesis. Moreover, Alx1del/del embryos exhibited disruption of frontonasal mesenchyme identity, with loss of expression of Pax7 and concomitant ectopic expression of the jaw mesenchyme regulators Lhx6 and Lhx8 in the developing lateral nasal processes. The function of ALX1 in patterning the frontonasal mesenchyme is partly complemented by ALX4, a paralogous ALX family transcription factor whose loss-of-function causes a milder and distinctive FND. Together, these data uncover previously unknown roles of ALX1 in periocular mesenchyme development and frontonasal mesenchyme patterning, providing novel insights into the pathogenic mechanisms of ALX1-related FND.
Collapse
Affiliation(s)
- Paul P. R. Iyyanar
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
| | - Zhaoming Wu
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
| | - Yu Lan
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
- Division of Plastic Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
- Departments of Pediatrics and Surgery, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Yueh-Chiang Hu
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
- Departments of Pediatrics and Surgery, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Rulang Jiang
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
- Division of Plastic Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
- Departments of Pediatrics and Surgery, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- *Correspondence: Rulang Jiang,
| |
Collapse
|
4
|
Guerrero-Santoro J, Khor JM, Açıkbaş AH, Jaynes JB, Ettensohn CA. Analysis of the DNA-binding properties of Alx1, an evolutionarily conserved regulator of skeletogenesis in echinoderms. J Biol Chem 2021; 297:100901. [PMID: 34157281 PMCID: PMC8319359 DOI: 10.1016/j.jbc.2021.100901] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 06/09/2021] [Accepted: 06/18/2021] [Indexed: 11/24/2022] Open
Abstract
Alx1, a homeodomain-containing transcription factor, is a highly conserved regulator of skeletogenesis in echinoderms. In sea urchins, Alx1 plays a central role in the differentiation of embryonic primary mesenchyme cells (PMCs) and positively regulates the transcription of most biomineralization genes expressed by these cells. The alx1 gene arose via duplication and acquired a skeletogenic function distinct from its paralog (alx4) through the exonization of a 41–amino acid motif (the D2 domain). Alx1 and Alx4 contain glutamine-50 paired-type homeodomains, which interact preferentially with palindromic binding sites in vitro. Chromatin immunoprecipitation sequencing (ChIP-seq) studies have shown, however, that Alx1 binds both to palindromic and half sites in vivo. To address this apparent discrepancy and explore the function of the D2 domain, we used an endogenous cis-regulatory module associated with Sp-mtmmpb, a gene that encodes a PMC-specific metalloprotease, to analyze the DNA-binding properties of Alx1. We find that Alx1 forms dimeric complexes on TAAT-containing half sites by a mechanism distinct from the well-known mechanism of dimerization on palindromic sites. We used transgenic reporter assays to analyze the functional roles of half sites in vivo and demonstrate that two sites with partially redundant functions are essential for the PMC-specific activity of the Sp-mtmmpb cis-regulatory module. Finally, we show that the D2 domain influences the DNA-binding properties of Alx1 in vitro, suggesting that the exonization of this motif may have facilitated the acquisition of new transcriptional targets and consequently a novel developmental function.
Collapse
Affiliation(s)
| | - Jian Ming Khor
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Ayşe Haruka Açıkbaş
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - James B Jaynes
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Charles A Ettensohn
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.
| |
Collapse
|
5
|
Pini J, Kueper J, Hu YD, Kawasaki K, Yeung P, Tsimbal C, Yoon B, Carmichael N, Maas RL, Cotney J, Grinblat Y, Liao EC. ALX1-related frontonasal dysplasia results from defective neural crest cell development and migration. EMBO Mol Med 2020; 12:e12013. [PMID: 32914578 PMCID: PMC7539331 DOI: 10.15252/emmm.202012013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 01/02/2023] Open
Abstract
A pedigree of subjects presented with frontonasal dysplasia (FND). Genome sequencing and analysis identified a p.L165F missense variant in the homeodomain of the transcription factor ALX1 which was imputed to be pathogenic. Induced pluripotent stem cells (iPSC) were derived from the subjects and differentiated to neural crest cells (NCC). NCC derived from ALX1L165F/L165F iPSC were more sensitive to apoptosis, showed an elevated expression of several neural crest progenitor state markers, and exhibited impaired migration compared to wild-type controls. NCC migration was evaluated in vivo using lineage tracing in a zebrafish model, which revealed defective migration of the anterior NCC stream that contributes to the median portion of the anterior neurocranium, phenocopying the clinical presentation. Analysis of human NCC culture media revealed a change in the level of bone morphogenic proteins (BMP), with a low level of BMP2 and a high level of BMP9. Soluble BMP2 and BMP9 antagonist treatments were able to rescue the defective migration phenotype. Taken together, these results demonstrate a mechanistic requirement of ALX1 in NCC development and migration.
Collapse
Affiliation(s)
- Jonathan Pini
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
- Shriners Hospital for Children, Boston, MA, USA
| | - Janina Kueper
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
- Shriners Hospital for Children, Boston, MA, USA
- Life and Brain Center, University of Bonn, Bonn, Germany
| | - Yiyuan David Hu
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
- Shriners Hospital for Children, Boston, MA, USA
| | - Kenta Kawasaki
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
- Shriners Hospital for Children, Boston, MA, USA
| | - Pan Yeung
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
- Shriners Hospital for Children, Boston, MA, USA
| | - Casey Tsimbal
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
- Shriners Hospital for Children, Boston, MA, USA
| | - Baul Yoon
- Departments of Integrative Biology, Neuroscience, and Genetics Ph.D. Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Nikkola Carmichael
- Department of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Richard L Maas
- Department of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Justin Cotney
- Genetics and Genome Sciences, UConn Health, Farmington, CT, USA
| | - Yevgenya Grinblat
- Departments of Integrative Biology, Neuroscience, and Genetics Ph.D. Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Eric C Liao
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA
- Shriners Hospital for Children, Boston, MA, USA
| |
Collapse
|
6
|
Hussain S, Umm-E-Kalsoom, Ullah I, Liaqat K, Nawaz S, Ahmad W. A Novel Missense Variant in the ALX4 Gene Underlies Mild to Severe Frontonasal Dysplasia in a Consanguineous Family. Genet Test Mol Biomarkers 2020; 24:217-223. [PMID: 32216639 DOI: 10.1089/gtmb.2019.0203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Background: Frontonasal dysplasia (FND) is a rare developmental disorder characterized by mild to severe changes in skull and brain structures. It is a phenotypically variable and heterogeneous disorder. This study was designed to provide a clinical and genetic analysis of FND in a consanguineous family of Pakistani origin. Methodology and Results: Affected individuals in the family showed characteristic features of frontonasal dysplasia type-2 (FND2), such as nasal bone hypoplasia, hypertelorism, and alopecia. Skull and brain imaging of affected members revealed ossification defects and various types of brain structural anomalies that created a split-brain. Sanger sequencing of the ALX4 gene revealed a homozygous missense variant [NM_021926.4: c.652C>T; p.(Arg218Trp)] in three affected members who demonstrated severe craniofacial anomalies. Heterozygous carriers in the family showed mild FND2 phenotypes. Conclusion: Clinical and genetic analysis of a family, exhibiting FND2 phenotypes, revealed several previously unreported clinical features and a novel missense variant in the ALX4 gene. These results will facilitate diagnosis and genetic counseling of the FND patients in the Pakistani population.
Collapse
Affiliation(s)
- Shabir Hussain
- Department of Biochemistry, Quaid-i-Azam University, Islamabad, Pakistan
| | - Umm-E-Kalsoom
- Department of Biochemistry, Hazara University, Mansehra, Pakistan
| | - Irfan Ullah
- Department of Biological Sciences, Shaheed Benazir Bhutto University, Upper Dir, Pakistan
| | - Khurram Liaqat
- Department of Biotechnology, Quaid-i-Azam University, Islamabad, Pakistan
| | - Shoaib Nawaz
- Department of Biotechnology, Quaid-i-Azam University, Islamabad, Pakistan
| | - Wasim Ahmad
- Department of Biochemistry, Quaid-i-Azam University, Islamabad, Pakistan
| |
Collapse
|
7
|
A Comprehensive review of genetic skeletal disorders reported from Pakistan: A brief commentary. Meta Gene 2019. [DOI: 10.1016/j.mgene.2019.100559] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
8
|
Umair M, Ullah A, Abbas S, Ahmad F, Basit S, Ahmad W. First direct evidence of involvement of a homozygous loss-of-function variant in the EPS15L1
gene underlying split-hand/split-foot malformation. Clin Genet 2018; 93:699-702. [DOI: 10.1111/cge.13152] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 10/03/2017] [Accepted: 10/05/2017] [Indexed: 11/29/2022]
Affiliation(s)
- M. Umair
- Department of Biochemistry, Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - A. Ullah
- Department of Biochemistry, Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - S. Abbas
- Department of Biochemistry, Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - F. Ahmad
- Department of Biochemistry, Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| | - S. Basit
- Center for Genetics and Inherited Diseases; Taibah University; Al Madinah Saudi Arabia
| | - W. Ahmad
- Department of Biochemistry, Faculty of Biological Sciences; Quaid-i-Azam University; Islamabad Pakistan
| |
Collapse
|
9
|
Ullah A, Umair M, E-Kalsoom U, Shahzad S, Basit S, Ahmad W. Exome sequencing revealed a novel nonsense variant in ALX3 gene underlying frontorhiny. J Hum Genet 2017; 63:97-100. [PMID: 29215096 DOI: 10.1038/s10038-017-0358-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/13/2017] [Accepted: 08/17/2017] [Indexed: 11/09/2022]
Abstract
Frontorhiny is one of the two forms of mid-facial malformations characterized by ocular hypertelorism, wide and short nasal ridge, bifid nasal tip, broad columella, widely separated nares, long and wide philtrum and V-shaped hairline. Sometimes these phenotypes are associated with ptosis and midline dermoid cysts. Frontorhiny inherits in an autosomal recessive pattern. Sequence variants in the Aristaless-like homeobox 3 (ALX3) gene underlying frontorhiny have been reported previously. Here, in the present study, we have investigated four patients in a consanguineous family of Pakistani origin segregating frontorhiny in autosomal recessive manner. Genome scan using 250k Nsp1 array followed by exome and Sanger sequence analysis revealed a novel homozygous nonsense variant (c.604C>T, p.Gln202*) in the ALX3 gene resulting in frontorhiny in the family. This is the first mutation in the ALX3 gene, underlying frontorhiny, in Pakistani population.
Collapse
Affiliation(s)
- Asmat Ullah
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University Islamabad, Islamabad, Pakistan
| | - Muhammad Umair
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University Islamabad, Islamabad, Pakistan
| | - Umm E-Kalsoom
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University Islamabad, Islamabad, Pakistan
| | - Shaheen Shahzad
- Department of Biotechnology, International Islamic University, Islamabad, Pakistan
| | - Sulman Basit
- Center for Genetics and Inherited Diseases, Taibah University Al Madinah, Al Munawarah, Saudi Arabia
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University Islamabad, Islamabad, Pakistan.
| |
Collapse
|
10
|
Farlie PG, Baker NL, Yap P, Tan TY. Frontonasal Dysplasia: Towards an Understanding of Molecular and Developmental Aetiology. Mol Syndromol 2016; 7:312-321. [PMID: 27920634 DOI: 10.1159/000450533] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2016] [Indexed: 01/09/2023] Open
Abstract
The complex anatomy of the skull and face arises from the requirement to support multiple sensory and structural functions. During embryonic development, the diverse component elements of the neuro- and viscerocranium must be generated independently and subsequently united in a manner that sustains and promotes the growth of the brain and sensory organs, while achieving a level of structural integrity necessary for the individual to become a free-living organism. While each of these individual craniofacial components is essential, the cranial and facial midline lies at a structural nexus that unites these disparately derived elements, fusing them into a whole. Defects of the craniofacial midline can have a profound impact on both form and function, manifesting in a diverse array of phenotypes and clinical entities that can be broadly defined as frontonasal dysplasias (FNDs). Recent advances in the identification of the genetic basis of FNDs along with the analysis of developmental mechanisms impacted by these mutations have dramatically altered our understanding of this complex group of conditions.
Collapse
Affiliation(s)
- Peter G Farlie
- Murdoch Childrens Research Institute, University of Melbourne, Parkville, Vic., Australia; Department of Paediatrics, University of Melbourne, Parkville, Vic., Australia
| | - Naomi L Baker
- Murdoch Childrens Research Institute, University of Melbourne, Parkville, Vic., Australia; Department of Paediatrics, University of Melbourne, Parkville, Vic., Australia
| | - Patrick Yap
- Victorian Clinical Genetics Service, Royal Children's Hospital, University of Melbourne, Parkville, Vic., Australia; Genetic Health Service New Zealand (Northern Hub), Auckland City Hospital, Auckland, New Zealand
| | - Tiong Y Tan
- Victorian Clinical Genetics Service, Royal Children's Hospital, University of Melbourne, Parkville, Vic., Australia; Department of Paediatrics, University of Melbourne, Parkville, Vic., Australia
| |
Collapse
|