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Álvarez LFG, Tenorio-Castaño J, Poletta FA, Santos-Simarro F, Arias P, Gallego N, Orioli IM, Mundlos S, Castilla EE, Martínez-Glez V, Martínez-Frías ML, Ruiz-Pérez VL, Nevado J, Lapunzina P. A large, ten-generation family with autosomal dominant preaxial polydactyly/triphalangeal thumb: Historical, clinical, genealogical, and molecular studies. Am J Med Genet A 2023; 191:100-107. [PMID: 36308343 DOI: 10.1002/ajmg.a.62994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 07/05/2022] [Accepted: 08/19/2022] [Indexed: 12/14/2022]
Abstract
We present a large, ten-generation family of 273 individuals with 84 people having preaxial polydactyly/triphalangeal thumb due to a pathogenic variant in the zone of polarizing activity regulatory sequence (ZRS) within the exon 5 of LMBR1. The causative change maps to position 396 of the ZRS, located at position c.423 + 4909C > T (chr7:156791480; hg38; LMBR1 ENST00000353442.10; rs606231153 NG_009240.2) in the intron 5 of LMBR1. The first affected individual with the disorder was traced back to mid-1700, when some settlers and workers established in Cervera de Buitrago, a small village about 82 km North to Madrid. Clinical and radiological studies of most of the affected members have been performed for 42 years (follow-up of the family by LFGA). Molecular studies have confirmed a pathogenic variant in the ZRS that segregates in this family. To the best of our knowledge, this is the largest family with preaxial polydactyly/triphalangeal thumb reported so far.
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Affiliation(s)
| | - Jair Tenorio-Castaño
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
- INGEMM-Idipaz, Institute of Medical and Molecular Genetics, Madrid, Spain
- ITHACA, European Reference Network, Brussels, Belgium
| | - Fernando A Poletta
- ECLAMC at CEMIC (Center for Medical Education and Clinical Research) and CONICET (National Council for Scientific and Technical Investigation), Buenos Aires, Argentina
- ECLAMC (Latin American Collaborative Study of Congenital Malformations) at INAGEMP (National Institute of Population Medical Genetics), Rio de Janeiro, Brazil
- Department of Genetics, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fernando Santos-Simarro
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
- INGEMM-Idipaz, Institute of Medical and Molecular Genetics, Madrid, Spain
- ITHACA, European Reference Network, Brussels, Belgium
| | - Pedro Arias
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
- INGEMM-Idipaz, Institute of Medical and Molecular Genetics, Madrid, Spain
| | - Natalia Gallego
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
- INGEMM-Idipaz, Institute of Medical and Molecular Genetics, Madrid, Spain
- ITHACA, European Reference Network, Brussels, Belgium
| | - Iêda Maria Orioli
- ECLAMC at CEMIC (Center for Medical Education and Clinical Research) and CONICET (National Council for Scientific and Technical Investigation), Buenos Aires, Argentina
- ECLAMC (Latin American Collaborative Study of Congenital Malformations) at INAGEMP (National Institute of Population Medical Genetics), Rio de Janeiro, Brazil
- Department of Genetics, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Stefan Mundlos
- Institute of Medical and Human Genetics, Charité Universitätsmedizin, Berlin, Germany
- Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Eduardo E Castilla
- ECLAMC at CEMIC (Center for Medical Education and Clinical Research) and CONICET (National Council for Scientific and Technical Investigation), Buenos Aires, Argentina
- ECLAMC (Latin American Collaborative Study of Congenital Malformations) at INAGEMP (National Institute of Population Medical Genetics), Rio de Janeiro, Brazil
- Department of Genetics, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Víctor Martínez-Glez
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
- INGEMM-Idipaz, Institute of Medical and Molecular Genetics, Madrid, Spain
- ITHACA, European Reference Network, Brussels, Belgium
| | | | - Víctor L Ruiz-Pérez
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
- ITHACA, European Reference Network, Brussels, Belgium
- Instituto de Investigaciones Biomédicas Alberto Sols, IIB-UAM, Madrid, Spain
| | - Julián Nevado
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
- INGEMM-Idipaz, Institute of Medical and Molecular Genetics, Madrid, Spain
- ITHACA, European Reference Network, Brussels, Belgium
| | - Pablo Lapunzina
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
- INGEMM-Idipaz, Institute of Medical and Molecular Genetics, Madrid, Spain
- ITHACA, European Reference Network, Brussels, Belgium
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Sun L, Rong X, Liu X, Yu Z, Zhang Q, Ren W, Yang G, Xu S. Evolutionary genetics of flipper forelimb and hindlimb loss from limb development-related genes in cetaceans. BMC Genomics 2022; 23:797. [DOI: 10.1186/s12864-022-09024-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 11/18/2022] [Indexed: 12/03/2022] Open
Abstract
Abstract
Background
Cetacean hindlimbs were lost and their forelimb changed into flippers characterized by webbed digits and hyperphalangy, thus allowing them to adapt to a completely aquatic environment. However, the underlying molecular mechanism behind cetacean limb development remains poorly understood.
Results
In the present study, we explored the evolution of 16 limb-related genes and their cis-regulatory elements in cetaceans and compared them with that of other mammals. TBX5, a forelimb specific expression gene, was identified to have been under accelerated evolution in the ancestral branches of cetaceans. In addition, 32 cetacean-specific changes were examined in the SHH signaling network (SHH, PTCH1, TBX5, BMPs and SMO), within which mutations could yield webbed digits or an additional phalange. These findings thus suggest that the SHH signaling network regulates cetacean flipper formation. By contrast, the regulatory activity of the SHH gene enhancer—ZRS in cetaceans—was significantly lower than in mice, which is consistent with the cessation of SHH gene expression in the hindlimb bud during cetacean embryonic development. It was suggested that the decreased SHH activity regulated by enhancer ZRS might be one of the reasons for hindlimb degeneration in cetaceans. Interestingly, a parallel / convergent site (D42G) and a rapidly evolving CNE were identified in marine mammals in FGF10 and GREM1, respectively, and shown to be essential to restrict limb bud size; this is molecular evidence explaining the convergence of flipper-forelimb and shortening or degeneration of hindlimbs in marine mammals.
Conclusions
We did evolutionary analyses of 16 limb-related genes and their cis-regulatory elements in cetaceans and compared them with those of other mammals to provide novel insights into the molecular basis of flipper forelimb and hindlimb loss in cetaceans.
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The pZRS non-coding regulatory mutation resulting in triphalangeal thumb-polysyndactyly syndrome changes the pattern of local interactions. Mol Genet Genomics 2022; 297:1343-1352. [PMID: 35821352 DOI: 10.1007/s00438-022-01921-2] [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: 11/08/2021] [Accepted: 06/18/2022] [Indexed: 10/17/2022]
Abstract
Herein, we report on a large Polish family presenting with a classical triphalangeal thumb-polysyndactyly syndrome (TPT-PS). This rare congenital limb anomaly is generally caused by microduplications encompassing the Sonic Hedgehog (SHH) limb enhancer, termed the zone of polarizing activity (ZPA) regulatory sequence (ZRS). Recently, a pathogenic variant in the pre-ZRS (pZRS), a conserved sequence located near the ZRS, has been described in a TPT-PS Dutch family. We performed targeted ZRS sequencing, array comparative genomic hybridization, and whole-exome sequencing. Next, we sequenced the recently described pZRS region. Finally, we performed a circular chromatin conformation capture-sequencing (4C-seq) assay on skin fibroblasts of one affected family member and control samples to examine potential alterations in the SHH regulatory domain and functionally characterize the identified variant. We found that all affected individuals shared a recently identified pathogenic point mutation in the pZRS region: NC_000007.14:g.156792782C>G (GRCh38/hg38), which is the same as in the Dutch family. The results of 4C-seq experiments revealed increased interactions within the whole SHH regulatory domain (SHH-LMBR1 TAD) in the patient compared to controls. Our study expands the number of TPT-PS families carrying a pathogenic alteration of the pZRS and underlines the importance of routine pZRS sequencing in the genetic diagnostics of patients with TPT-PS or similar phenotypes. The pathogenic mutation causative for TPT-PS in our patient gave rise to increased interactions within the SHH regulatory domain in yet unknown mechanism.
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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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Jin JY, Wu PF, Luo FM, Guo BB, Zeng L, Fan LL, Tang JY, Xiang R. GLIS Family Zinc Finger 1 was First Linked With Preaxial Polydactyly I in Humans by Stepwise Genetic Analysis. Front Cell Dev Biol 2022; 9:781388. [PMID: 35087831 PMCID: PMC8787328 DOI: 10.3389/fcell.2021.781388] [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: 09/22/2021] [Accepted: 12/02/2021] [Indexed: 11/27/2022] Open
Abstract
Background: Preaxial polydactyly (PPD) is one of the most common developmental malformations, with a prevalence of 0.8–1.4% in Asians. PPD is divided into four types, PPD I–IV, and PPD I is the most frequent type. Only six loci (GLI1, GLI3, STKLD1, ZRS, pre-ZRS, and a deletion located 240 kb from SHH) have been identified in non-syndromic PPD cases. However, pathogenesis of most PPD patients has never been investigated. This study aimed to understand the genetic mechanisms involved in the etiology of PPD I in a family with multiple affected members. Methods: We recruited a PPD I family (PPD001) and used stepwise genetic analysis to determine the genetic etiology. In addition, for functional validation of the identified GLIS1 variant, in vitro studies were conducted. GLIS1 variants were further screened in additional 155 PPD cases. Results: We identified a GLIS1 variant (NM_147193: c.1061G > A, p.R354H) in the PPD001 family. In vitro studies showed that this variant decreased the nuclear translocation of GLIS1 and resulted in increased cell viability and migration. RNA sequencing revealed abnormal TBX4 and SFRP2 expression in 293T cells transfected with mutant GLIS1. Additionally, we identified a GLIS1 variant (c.664G > A, p.D222N) in another PPD case. Conclusion: We identified two GLIS1 variants in PPD I patients and first linked GLIS1 with PPD I. Our findings contributed to future molecular and clinical diagnosis of PPD and deepened our knowledge of this disease.
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Affiliation(s)
- Jie-Yuan Jin
- School of Life Sciences, Central South University, Changsha, China
| | - Pan-Feng Wu
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
| | - Fang-Mei Luo
- School of Life Sciences, Central South University, Changsha, China
| | - Bing-Bing Guo
- School of Life Sciences, Central South University, Changsha, China
| | - Lei Zeng
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
| | - Liang-Liang Fan
- School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Ju-Yu Tang
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
| | - Rong Xiang
- School of Life Sciences, Central South University, Changsha, China.,Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
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Zeng L, Jin JY, Luo FM, Sheng Y, Wu PF, Xiang R. ZPA Regulatory Sequence Variants in Chinese Patients With Preaxial Polydactyly: Genetic and Clinical Characteristics. Front Pediatr 2022; 10:797978. [PMID: 35652055 PMCID: PMC9149355 DOI: 10.3389/fped.2022.797978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 03/29/2022] [Indexed: 11/29/2022] Open
Abstract
Preaxial polydactyly (PPD) is a common congenital abnormality with an incidence of 0.8-1.4% in Asians, characterized by the presence of extra digit(s) on the preaxial side of the hand or foot. PPD is genetically classified into four subtypes, PPD type I-IV. Variants in six genes/loci [including GLI family zinc finger 3 (GLI3), ZPA regulatory sequence (ZRS), and pre-ZRS region] have been identified in PPD cases. Among these loci, ZRS is, perhaps, the most special and well known, but most articles only reported one or a few cases. There is a lack of reports on the ZRS-variant frequency in patients with PPD. In this study, we recruited 167 sporadic or familial cases (including 154 sporadic patients and 13 families) with PPD from Central-South China and identified four ZRS variants in four patients (2.40%, 4/167), including two novel variants (ZRS131A > T/chr7:g.156584439A > T and ZRS474C > G/chr7:g.156584096C > G) and two known variants (ZRS428T > A/chr7:g.156584142T > A and ZRS619C > T/chr7:g.156583951C > T). ZRS131A > T and ZRS428T > A were detected in PPD I cases and ZRS474C > G and ZRS619C > T combinedly acted to cause PPD II. The detectable rate of ZRS variants in PPD I was 1.60% (2/125), while PPD II was significantly higher (9.52%, 2/21). Three bilateral PPD cases harbored ZRS variants (13.64%, 3/22), suggesting that bilateral PPD was more possibly caused by genetic etiologies. This study identified two novel ZRS variants, further confirmed the association between ZRS and PPD I and reported a rare PPD II case resulted from the compound heterozygote of ZRS. This investigation preliminarily evaluated a ZRS variants rate in patients with PPD and described the general picture of PPD in Central-South China.
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Affiliation(s)
- Lei Zeng
- Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, China
| | - Jie-Yuan Jin
- School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
| | - Fang-Mei Luo
- School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China
| | - Yue Sheng
- School of Life Sciences, Central South University, Changsha, China
| | - Pan-Feng Wu
- Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Rong Xiang
- Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.,School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
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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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Zhang SJ, Lin HB, Jiang QX, He SZ, Lyu GR. Prenatal diagnosis of triphalangeal thumb-polysyndactyly syndrome by ultrasonography combined with genetic testing: A case report. World J Clin Cases 2021; 9:6832-6838. [PMID: 34447832 PMCID: PMC8362503 DOI: 10.12998/wjcc.v9.i23.6832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 06/04/2021] [Accepted: 06/16/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Triphalangeal thumb-polysyndactyly syndrome (TPT-PS) is a rare type of congenital limb deformity, and most studies focus on the genetics. Case reports of the sonographic characteristics of TPT-PS during pregnancy are rare.
CASE SUMMARY A 30-year-old woman (G3P1) who had pregnancies with TPT-PS fetuses is presented. The possibility of TPT-PS was shown by ultrasound performed at the 19th wk of pregnancy, featuring hands with six metacarpals, an extra digit at the 5th finger side, and an abnormally widened thumb. Whole-exome sequencing was subsequently conducted. The results showed that exons 1-17 of the LMBR1 gene had a heterozygous duplication, with a length of approximately 253 kb.
CONCLUSION We suggest prenatal ultrasound examination combined with genetic testing to diagnose TPT-PS accurately and to help clinicians and patients make decisions.
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Affiliation(s)
- Shi-Jie Zhang
- Department of Ultrasound, The Second Affiliated Hospital of Fujian Medical University, Quanzhou 362000, Fujian Province, China
| | - Hai-Bin Lin
- Department of Ultrasound, Jinjiang Municipal Hospital, Quanzhou 362000, Fujian Province, China
| | - Qiu-Xia Jiang
- Department of Ultrasound, Quanzhou Women’s and Children’s Hospital, Quanzhou 362000, Fujian Province, China
- Collaborative Innovation Center for Maternal and Infant Health Service, Application Technology of Education Ministry, Quanzhou Medical College, Quanzhou 362000, Fujian Province, China
| | - Shao-Zheng He
- Department of Ultrasound, The Second Affiliated Hospital of Fujian Medical University, Quanzhou 362000, Fujian Province, China
| | - Guo-Rong Lyu
- Department of Ultrasound, The Second Affiliated Hospital of Fujian Medical University, Quanzhou 362000, Fujian Province, China
- Department of Ultrasound, Jinjiang Municipal Hospital, Quanzhou 362000, Fujian Province, China
- Department of Ultrasound, Quanzhou Women’s and Children’s Hospital, Quanzhou 362000, Fujian Province, China
- Collaborative Innovation Center for Maternal and Infant Health Service, Application Technology of Education Ministry, Quanzhou Medical College, Quanzhou 362000, Fujian Province, China
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Cong Q, Liu Y, Zhou T, Zhou Y, Xu R, Cheng C, Chung HS, Yan M, Zhou H, Liao Z, Gao B, Bocobo GA, Covington TA, Song HJ, Su P, Yu PB, Yang Y. A self-amplifying loop of YAP and SHH drives formation and expansion of heterotopic ossification. Sci Transl Med 2021; 13:13/599/eabb2233. [PMID: 34162750 PMCID: PMC8638088 DOI: 10.1126/scitranslmed.abb2233] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 12/03/2020] [Accepted: 05/30/2021] [Indexed: 12/15/2022]
Abstract
Heterotopic ossification (HO) occurs as a common complication after injury or in genetic disorders. The mechanisms underlying HO remain incompletely understood, and there are no approved prophylactic or secondary treatments available. Here, we identify a self-amplifying, self-propagating loop of Yes-associated protein (YAP)-Sonic hedgehog (SHH) as a core molecular mechanism underlying diverse forms of HO. In mouse models of progressive osseous heteroplasia (POH), a disease caused by null mutations in GNAS, we found that Gnas-/- mesenchymal cells secreted SHH, which induced osteoblast differentiation of the surrounding wild-type cells. We further showed that loss of Gnas led to activation of YAP transcription activity, which directly drove Shh expression. Secreted SHH further induced YAP activation, Shh expression, and osteoblast differentiation in surrounding wild-type cells. This self-propagating positive feedback loop was both necessary and sufficient for HO expansion and could act independently of Gnas in fibrodysplasia ossificans progressiva (FOP), another genetic HO, and nonhereditary HO mouse models. Genetic or pharmacological inhibition of YAP or SHH abolished HO in POH and FOP and acquired HO mouse models without affecting normal bone homeostasis, providing a previously unrecognized therapeutic rationale to prevent, reduce, and shrink HO.
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Affiliation(s)
- Qian Cong
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA
| | - Yuchen Liu
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA
| | - Taifeng Zhou
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA
| | - Yaxing Zhou
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA
| | - Ruoshi Xu
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA
| | - Caiqi Cheng
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA
| | - Hye Soo Chung
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA
| | - Meijun Yan
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - Hang Zhou
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - Zhiheng Liao
- Department of Orthopaedic Surgery, Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China
| | - Bo Gao
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA
| | - Geoffrey A Bocobo
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - Taylor A Covington
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - Hyeon Ju Song
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - Peiqiang Su
- Department of Orthopaedic Surgery, Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China
| | - Paul B Yu
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - Yingzi Yang
- Department of Developmental Biology, Harvard School of Dental Medicine, Harvard Stem Cell Institute, 188 Longwood Ave., Boston, MA 02115, USA.
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Zu B, Zhang X, Xu Y, Xiang Y, Wang Z, Cai H, Wang B, You G, Fu Q. Identification of the genetic basis of sporadic polydactyly in China by targeted sequencing. Comput Struct Biotechnol J 2021; 19:3482-3490. [PMID: 34194672 PMCID: PMC8225516 DOI: 10.1016/j.csbj.2021.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 05/26/2021] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
Purpose Polydactyly is a highly heterogeneous group of skeletal deformities in clinical and genetic background. The variation spectrum in Chinese sporadic polydactyly has not been comprehensively analyzed. To elucidate genetic variation spectrum and genotype-phenotype correlations in Chinese patients with polydactyly, we conducted comprehensive genetic analysis of patients nationwide using targeted sequencing. Methods A total of 181 patients diagnosed with polydactylies were recruited. We designed a targeted capture panel for sequencing 721 genes that are associated with the pathogenesis of skeletal dysplasia. We performed rigorous variant- and gene-level filtrations to identify potentially damaging variants, followed by enrichment analysis and gene prioritization. Results A total of 568 deleterious variants of 293 genes were identified in 173 of 181 patients with a positive rate of 95.6% by targeted sequencing. For each sample, an average of 3.17 deleterious variants were identified. Especially, 14 pathogenic or likely pathogenic variants were identified in 10 genes in 14 patients out of the 181 patients, providing a positive molecular diagnostic rate of 7.7%. Conclusion Targeted sequencing analysis provides a high efficiency approach for the genetic diagnosis of polydactyly. This is the largest next generation sequencing study performed to date in patients with polydactyly and represents the genetic basis of polydactyly typically encountered in genetics clinics.
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Affiliation(s)
- Bailing Zu
- Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Xiaoqing Zhang
- Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Yunlan Xu
- Department of Pediatric Orthopedic, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Ying Xiang
- Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Zhigang Wang
- Department of Pediatric Orthopedic, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Haiqing Cai
- Department of Pediatric Orthopedic, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Bo Wang
- Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Guoling You
- Department of Laboratory Medicine, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Qihua Fu
- Pediatric Translational Medicine Institute, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
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11
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Zu B, Wang Z, Xu Y, You G, Fu Q. Nonframeshifting indel variations in polyalanine repeat of
HOXD13
gene underlies hereditary limb malformation for two Chinese families. Dev Dyn 2021; 250:1220-1228. [DOI: 10.1002/dvdy.310] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 01/16/2021] [Accepted: 01/17/2021] [Indexed: 12/18/2022] Open
Affiliation(s)
- Bailing Zu
- Pediatric Translational Medicine Institute, Shanghai Children's Medical Center Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Zhigang Wang
- Department of Pediatric Orthopedic Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Yunlan Xu
- Department of Pediatric Orthopedic Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Guoling You
- Department of Laboratory Medicine Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Qihua Fu
- Pediatric Translational Medicine Institute, Shanghai Children's Medical Center Shanghai Jiao Tong University School of Medicine Shanghai China
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12
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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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13
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Xu J, Wu J, Teng X, Cai L, Yuan H, Chen X, Hu M, Wang X, Jiang N, Chen H. Large duplication in LMBR1 gene in a large Chinese pedigree with triphalangeal thumb polysyndactyly syndrome. Am J Med Genet A 2020; 182:2117-2123. [PMID: 32662247 DOI: 10.1002/ajmg.a.61757] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 04/30/2020] [Accepted: 05/28/2020] [Indexed: 12/18/2022]
Abstract
Polydactyly and syndactyly are digital abnormalities in limb-associated birth defects usually caused by genetic disorders. In this study, a five-generation Chinese pedigree was found with triphalangeal thumb polysyndactyly syndrome (TPTPS), showing an autosomal dominant pattern of inheritance. We utilized linkage analysis and whole genome sequencing (WGS) for the genetic diagnosis of this pedigree. Linkage analysis was performed using a genome-wide single nucleotide polymorphism (SNP) chip and three genomic regions were identified in chromosomes 2, 6, and 7 with significant linkage signals. WGS discovered a copy number variation (CNV) mutation caused by a large duplication region at the tail of chromosome 7 located in exons 1-5 of the LMBR1 gene, including the zone of polarizing activity regulatory sequence (ZRS), with a length of approximately 180 kb. A real-time polymerase chain reaction (PCR) assay confirmed the duplication. The findings of our study supported the notion that large duplications including the ZRS caused TPTPS. Our study showed that linkage analysis in combination with WGS could successfully identify the disease locus and causative mutation in TPTPS, which could help elucidate the molecular mechanisms and genotype-phenotype correlations in polydactyly.
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Affiliation(s)
- Jihai Xu
- Department of Hand Surgery, Ningbo No. 6 Hospital, Ningbo, China
| | - Jing Wu
- Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
| | - Xiaofeng Teng
- Department of Hand Surgery, Ningbo No. 6 Hospital, Ningbo, China
| | - Libing Cai
- Department of Hand Surgery, Ningbo No. 6 Hospital, Ningbo, China
| | - Huizong Yuan
- Department of Hand Surgery, Ningbo No. 6 Hospital, Ningbo, China
| | - Xiaokun Chen
- Department of Orthopedic Trauma, Peking University People Hospital, Beijing, China
| | - Mu Hu
- Department of Orthopedics, Ruijin Hospital North, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Xin Wang
- Department of Hand Surgery, Ningbo No. 6 Hospital, Ningbo, China
| | - Ning Jiang
- Department of Biostatistics and Computational Biology, SKLG, School of Life Sciences, Fudan University, Shanghai, China
| | - Hong Chen
- Department of Hand Surgery, Ningbo No. 6 Hospital, Ningbo, China
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14
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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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15
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Perenthaler E, Yousefi S, Niggl E, Barakat TS. Beyond the Exome: The Non-coding Genome and Enhancers in Neurodevelopmental Disorders and Malformations of Cortical Development. Front Cell Neurosci 2019; 13:352. [PMID: 31417368 PMCID: PMC6685065 DOI: 10.3389/fncel.2019.00352] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 07/16/2019] [Indexed: 12/22/2022] Open
Abstract
The development of the human cerebral cortex is a complex and dynamic process, in which neural stem cell proliferation, neuronal migration, and post-migratory neuronal organization need to occur in a well-organized fashion. Alterations at any of these crucial stages can result in malformations of cortical development (MCDs), a group of genetically heterogeneous neurodevelopmental disorders that present with developmental delay, intellectual disability and epilepsy. Recent progress in genetic technologies, such as next generation sequencing, most often focusing on all protein-coding exons (e.g., whole exome sequencing), allowed the discovery of more than a 100 genes associated with various types of MCDs. Although this has considerably increased the diagnostic yield, most MCD cases remain unexplained. As Whole Exome Sequencing investigates only a minor part of the human genome (1–2%), it is likely that patients, in which no disease-causing mutation has been identified, could harbor mutations in genomic regions beyond the exome. Even though functional annotation of non-coding regions is still lagging behind that of protein-coding genes, tremendous progress has been made in the field of gene regulation. One group of non-coding regulatory regions are enhancers, which can be distantly located upstream or downstream of genes and which can mediate temporal and tissue-specific transcriptional control via long-distance interactions with promoter regions. Although some examples exist in literature that link alterations of enhancers to genetic disorders, a widespread appreciation of the putative roles of these sequences in MCDs is still lacking. Here, we summarize the current state of knowledge on cis-regulatory regions and discuss novel technologies such as massively-parallel reporter assay systems, CRISPR-Cas9-based screens and computational approaches that help to further elucidate the emerging role of the non-coding genome in disease. Moreover, we discuss existing literature on mutations or copy number alterations of regulatory regions involved in brain development. We foresee that the future implementation of the knowledge obtained through ongoing gene regulation studies will benefit patients and will provide an explanation to part of the missing heritability of MCDs and other genetic disorders.
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Affiliation(s)
- Elena Perenthaler
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
| | - Soheil Yousefi
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
| | - Eva Niggl
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
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16
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Al-Qattan MM. A Review of the Genetics and Pathogenesis of Syndactyly in Humans and Experimental Animals: A 3-Step Pathway of Pathogenesis. BIOMED RESEARCH INTERNATIONAL 2019; 2019:9652649. [PMID: 31637260 PMCID: PMC6766129 DOI: 10.1155/2019/9652649] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/23/2019] [Accepted: 09/01/2019] [Indexed: 12/30/2022]
Abstract
Embryology of normal web space creation and the genetics of syndactyly in humans and experimental animals are well described in the literature. In this review, the author offers a 3-step pathway of pathogenesis for syndactyly. The first step is initiated either by the overactivation of the WNT canonical pathway or the suppression of the Bone Morphogenetic Protein (BMP) canonical pathway. This leads to an overexpression of Fibroblast Growth Factor 8 (FGF8). The final step is the suppression of retinoic acid in the interdigital mesenchyme leading to suppression of both apoptosis and extracellular matrix (ECM) degradation, resulting in syndactyly.
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Affiliation(s)
- Mohammad M Al-Qattan
- Professor of Hand Surgery, King Saud University, Riyadh, Saudi Arabia
- King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
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17
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Yip RK, Chan D, Cheah KS. Mechanistic insights into skeletal development gained from genetic disorders. Curr Top Dev Biol 2019; 133:343-385. [DOI: 10.1016/bs.ctdb.2019.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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18
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Umair M, Ahmad F, Bilal M, Ahmad W, Alfadhel M. Clinical Genetics of Polydactyly: An Updated Review. Front Genet 2018; 9:447. [PMID: 30459804 PMCID: PMC6232527 DOI: 10.3389/fgene.2018.00447] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 09/14/2018] [Indexed: 01/17/2023] Open
Abstract
Polydactyly, also known as hyperdactyly or hexadactyly is the most common hereditary limb anomaly characterized by extra fingers or toes, with various associated morphologic phenotypes as part of a syndrome (syndromic polydactyly) or may occur as a separate event (non-syndromic polydactyly). Broadly, the non-syndromic polydactyly has been classified into three types, i.e.; preaxial polydactyly (radial), central polydactyly (axial), and postaxial polydactyly (ulnar). Mostly inherited as an autosomal dominant entity with variable penetrance and caused by defects that occur in the anterior-posterior patterning of limb development. In humans, to-date at least 10 loci and six genes causing non-syndromic polydactyly have been identified, including the ZNF141, GLI3, MIPOL1, IQCE, PITX1, and the GLI1. In the present review, clinical, genetic and molecular characterization of the polydactyly types has been presented including the recent genes and loci identified for non-syndromic polydactyly. This review provides an overview of the complex genetic mechanism underlie polydactyly and might help in genetic counseling and quick molecular diagnosis.
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Affiliation(s)
- Muhammad Umair
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Farooq Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Muhammad Bilal
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Majid Alfadhel
- Division of Genetics, Department of Pediatrics, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
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