Mutations in EDA and EDAR Genes in a Large Mexican Hispanic Cohort with Hypohidrotic Ectodermal Dysplasia

Pathogenic EDA Mutations in Chinese Han Families With Hypohidrotic Ectodermal Dysplasia and Genotype-Phenotype: A Correlation Analysis

Background

This study aimed to investigate the genetic causes of hypohidrotic ectodermal dysplasia (HED) in two families and elucidate the molecular pathogenesis of HED in Chinese Han patients.

Methods

Whole-exome sequencing (WES) was used to screen HED-related genes in two family members, followed by confirmatory Sanger sequencing. Bioinformatics analysis was performed for the mutations. We reviewed HED-related articles in PubMed. χ²- and Fisher's tests were used to analyze the genotype–phenotype correlations.

Results

(1) WES identified EDA missense mutations [c.1127 C > T (p.T376M; NM_001005609)] in family 1 and an EDA nonframeshift deletion mutation [c.648_683delACCTGGTCCTCCAGGTCCTCCTGGTCCTCAAGGACC (p.216_228delPPGPPGPPGPQGP; NM_001005609)] in family 2. Sanger sequencing validated the results. ANNOVAR (ANNOtate VARiation) annotation indicated that c.1127 c > T was a deleterious mutation. (2) The review of published papers revealed 68 novel mutations related to HED: 57 (83.8%) were EDA mutations, 8 (11.8%) were EDAR mutations, 2 (2.9%) were EDARADD mutations, 1 (1.5%) was a WNT10A mutation, 31 (45.6%) were missense mutations, 23 (33.8%) were deletion mutations, and 1 (1.5%) was an indel. Genotype–phenotype correlation analysis revealed that patients with EDA missense mutations had a higher frequency of hypohidrosis (P = 0.021).

Conclusions

This study identified two EDA gene mutations in two Chinese Han HED families and provides a foundation for genetic diagnosis and counseling.

EDA, EDAR, EDARADD and WNT10A allelic variants in patients with ectodermal derivative impairment in the Spanish population

BACKGROUND

Ectodermal dysplasias (ED) are a group of genetic conditions affecting the development and/or homeostasis of two or more ectodermal derivatives. An attenuated phenotype is considered a non-syndromic trait when the patient is affected by only one impaired ectodermal structure, such as in non-syndromic tooth agenesis (NSTA) disorder. Hypohidrotic ectodermal dysplasia (HED) is the most highly represented ED. X-linked hypohidrotic ectodermal dysplasia (XLHED) is the most common subtype, with an incidence of 1/50,000-100,000 males, and is associated with the EDA gene (Xq12-q13.1); the dominant and recessive subtypes involve the EDAR (2q13) and EDARADD (1q42.3) genes, respectively. The WNT10A gene (2q35) is associated more frequently with NSTA. Our goal was to determine the mutational spectrum in a cohort of 72 Spanish patients affected by one or more ectodermal derivative impairments referred to as HED (63/72) or NSTA (9 /72) to establish the prevalence of the allelic variants of the four most frequently associated genes. Sanger sequencing of the EDA, EDAR, EDARADD and WNT10A genes and multiplex ligation-dependent probe amplification (MLPA) were performed.

RESULTS

A total of 61 children and 11 adults, comprising 50 males and 22 females, were included. The average ages were 5.4 and 40.2 years for children and adults, respectively. A molecular basis was identified in 51/72 patients, including 47/63 HED patients, for whom EDA was the most frequently involved gene, and 4/9 NSTA patients, most of whom had variants of WNT10A. Among all the patients, 37/51 had variants of EDA, 8/51 had variants of the WNT10A gene, 4/51 had variants of EDAR and 5/51 had variants of EDARADD. In 42/51 of cases, the variants were inherited according to an X-linked pattern (27/42), with the remaining showing an autosomal dominant (10/42) or autosomal recessive (5/42) pattern. Among the NSTA patients, 3/9 carried pathogenic variants of WNT10A and 1/9 carried EDA variants. A total of 60 variants were detected in 51 patients, 46 of which were different, and out of these 46 variants, 12 were novel.

CONCLUSIONS

This is the only molecular study conducted to date in the Spanish population affected by ED. The EDA, EDAR, EDARADD and WNT10A genes constitute the molecular basis in 70.8% of patients with a 74.6% yield in HED and 44.4% in NSTA. Twelve novel variants were identified. The WNT10A gene has been confirmed as the second molecular candidate that has been identified and accounts for one-half of non-EDA patients and one-third of NSTA patients. Further studies using next generation sequencing (NGS) will help to identify other contributory genes in the remaining uncharacterized Spanish patients.

Deleterious Variants in WNT10A, EDAR, and EDA Causing Isolated and Syndromic Tooth Agenesis: A Structural Perspective from Molecular Dynamics Simulations

The dental abnormalities are the typical features of many ectodermal dysplasias along with congenital malformations of nails, skin, hair, and sweat glands. However, several reports of non-syndromic/isolated tooth agenesis have also been found in the literature. The characteristic features of hypohidrotic ectodermal dysplasia (HED) comprise of hypodontia/oligodontia, along with hypohidrosis/anhidrosis, and hypotrichosis. Pathogenic variants in EDA, EDAR, EDARADD, and TRAF6, cause the phenotypic expression of HED. Genetic alterations in EDA and WNT10A cause particularly non-syndromic/isolated oligodontia. In the current project, we recruited 57 patients of 17 genetic pedigrees (A-Q) from different geographic regions of the world, including Pakistan, Egypt, Saudi Arabia, and Syria. The molecular investigation of different syndromic and non-syndromic dental conditions, including hypodontia, oligodontia, generalized odontodysplasia, and dental crowding was carried out by using exome and Sanger sequencing. We have identified a novel missense variant (c.311G>A; p.Arg104His) in WNT10A in three oligodontia patients of family A, two novel sequence variants (c.207delinsTT, p.Gly70Trpfs*25 and c.1300T>G; p.Try434Gly) in EDAR in three patients of family B and four patients of family C, respectively. To better understand the structural and functional consequences of missense variants in WNT10A and EDAR on the stability of the proteins, we have performed extensive molecular dynamic (MD) simulations. We have also identified three previously reported pathogenic variants (c.1076T>C; p.Met359Thr), (c.1133C>T; p.Thr378Met) and (c.594_595insC; Gly201Argfs*39) in EDA in family D (four patients), E (two patients) and F (one patient), correspondingly. Presently, our data explain the genetic cause of 18 syndromic and non-syndromic tooth agenesis patients in six autosomal recessive and X-linked pedigrees (A-F), which expand the mutational spectrum of these unique clinical manifestations.

Turkish Ectodermal Dysplasia Cohort: From Phenotype to Genotype in 17 Families

Hypohidrotic or anhidrotic ectodermal dysplasia (HED/EDA) is characterized by impaired development of the hair, teeth, or sweat glands. HED/EDA is inherited in an X-linked, autosomal dominant, or autosomal recessive pattern and caused by the pathogenic variants in 4 genes: EDA, EDAR, EDARADD, and WNT10A. The aim of the present study was to perform molecular screening of these 4 genes in a cohort of Turkish individuals diagnosed with HED/EDA. We screened for pathogenic variants of WNT10A, EDA, EDAR, and EDARADD through Sanger sequencing. We further assessed the clinical profiles of the affected individuals in order to establish phenotype-genotype correlation. In 17 (63%) out of 27 families, 17 pathogenic variants, 8 being novel, were detected in the 4 well-known ectodermal dysplasia genes. EDAR and EDA variants were identified in 6 families each, WNT10A variants in 4, and an EDARADD variant in 1, accounting for 35.3, 35.3, 23.5, and 5.9% of mutation-positive families, respectively. The low mutation detection rate of the cohort and the number of the EDAR pathogenic variants being as high as the EDA ones were the most noteworthy findings which could be attributed to the high consanguinity rate.

Next generation sequencing reveals a novel nonsense mutation in MSX1 gene related to oligodontia

Tooth agenesis is one of the most common craniofacial disorders in humans. More than 350 genes have been associated with teeth development. In this study, we enrolled 60 child patients (age 13 to 17) with various types of tooth agenesis. Whole gene sequences of PAX9, MSX1, AXIN2, EDA, EDAR and WNT10a genes were sequenced by next generation sequencing on the Illumina MiSeq platform. We found previously undescribed heterozygous nonsense mutation g.8177G>T (c.610G>T) in MSX1 gene in one child. Mutation was verified by Sanger sequencing. Sequencing analysis was performed in other family members of the affected child. All family members carrying g.8177G>T mutation suffered from oligodontia (missing more than 6 teeth excluding third molars). Mutation g.8177G>T leads to a stop codon (p.E204X) and premature termination of Msx1 protein translation. Based on previous in vitro experiments on mutation disrupting function of Msx1 homeodomain, we assume that the heterozygous g.8177G>T nonsense mutation affects the amount and function of Msx1 protein and leads to tooth agenesis.

Gene screening facilitates diagnosis of complicated symptoms: A case report

Gene mutation has an important role in disease pathogenesis; therefore, genetic screening is a useful tool for diagnosis. The present study screened pathogenic genes, ectodysplasin A (EDA) and lamin A/C (LMNA), in a patient with suspected syndromic hearing impairment and various other symptoms including tooth and skin abnormalities. Large-scale sequencing of 438 deafness-associated genes and whole-genome sequencing was also performed. The present findings did not identify copy number variation and mutations in EDA; therefore, excluding the possibility of EDA-initiated ectodermal dysplasia syndrome. A synonymous mutation in LMNA, possibly due to a splicing abnormality, did not elucidate the pathogenesis of Hutchinson-Gilford progeria syndrome. Whole-genome sequencing revealed copy number variations or mutations in various candidate genes which may elucidate part of the symptoms observed. The copy number variations and mutations were also used to identify single nucleotide variations (SNVs) in crystallin mu (CRYM), RAB3 GTPase activating protein catalytic subunit 1 (RAB3GAP1) and Wnt family member 10A (WNT10A), implicated in deafness, hypogonadism and tooth/skin abnormalities, respectively. The importance of an existing SNV in CRYM and a novel SNV in RAB3GAP1 in pathogenesis remains to be further elucidated. The WNT10A p.G213S mutation was confirmed to be the etiological cause of tooth agenesis and ectodermal dysplasia as previously described. It was concluded that a mutation in WNT10A may be the reason for some of the symptoms observed in the patient; however, other genes may also be involved for other symptoms. The findings of the present study provide putative gene mutations that require further investigation in order to determine their roles in pathogenesis.

Mutational spectrum in 101 patients with hypohidrotic ectodermal dysplasia and breakpoint mapping in independent cases of rare genomic rearrangements

Hypohidrotic ectodermal dysplasia (HED), a rare and heterogeneous hereditary disorder, is characterized by deficient development of multiple ectodermal structures including hair, sweat glands and teeth. If caused by mutations in the genes EDA, EDA1R or EDARADD, phenotypes are often very similar as the result of a common signaling pathway. Single-nucleotide polymorphisms (SNPs) affecting any gene product in this pathway may cause inter- and intrafamilial variability. In a cohort of 124 HED patients, genotyping was attempted by Sanger sequencing of EDA, EDA1R, EDARADD, TRAF6 and EDA2R and by multiplex ligation-dependent probe amplification (MLPA). Pathogenic mutations were detected in 101 subjects with HED, affecting EDA, EDA1R and EDARADD in 88%, 9% and 3% of the cases, respectively, and including 23 novel mutations. MLPA revealed exon copy-number variations in five unrelated HED families (two deletions and three duplications). In four of them, the genomic breakpoints could be localized. The EDA1R variant rs3827760 (p.Val370Ala), known to lessen HED-related symptoms, was found only in a single individual of Asian origin, but in none of the 123 European patients. Another SNP, rs1385699 (p.Arg57Lys) in EDA2R, however, appeared to have some impact on the hair phenotype of European subjects with EDA mutations.