Genetic diagnosis for X-linked hypohidrotic ectodermal dysplasia family with a novel Ectodysplasin A gene mutation

Two novel ectodysplasin A gene mutations and prenatal diagnosis of X-linked hypohidrotic ectodermal dysplasia

Background

Hypohidrotic ectodermal dysplasia (HED) is mainly caused by ectodysplasin A (EDA) gene mutation. Fetus with genetic deficiency of EDA can be prenatally corrected. This study aimed at revealing the pathogenesis of two HED families and making a prenatal diagnosis for one pregnant female carrier.

Designs

Genomic DNA was extracted from two HED patients and sequenced using whole exome sequencing (WES). The detected mutations were confirmed in patients and family members using Sanger sequencing. The expression of soluble ectodysplasin A1 (EDA1) protein was studied by western blot. The transcriptional activity of NF‐κB pathway was tested by dual luciferase assay. The genomic DNA of fetus was extracted from shed chorion cells and EDA gene was screened through Sanger sequencing.

Results

We identified two novel EDA mutations: c.1136T>C (p.Phe379Ser) and c.[866G>C;868A>T] (p.[Arg289Pro;Ser290Cys]). Further examinations revealed that these two mutated EDA1 proteins showed completely impaired solubility, and the transcriptional NF‐κB activation induced by these missense mutant‐type EDA1 proteins was significantly reduced compared with wild‐type EDA1. Furthermore, the analysis of amniotic fluid samples from a pregnant heterozygote indicated that the fetus was a c.1136T>C mutation female carrier.

Conclusions

This study extended the mutation spectrum of X‐linked hypohidrotic ectodermal dysplasia (XLHED) and applied prenatal diagnosis for the pregnant carrier, which can be helpful in genetic counseling, prenatal diagnosis, and intervention for the XLHED family.

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.

Genetic diagnosis for X-linked hypohidrotic ectodermal dysplasia family with a novel Ectodysplasin A gene mutation

AIM

To make a gene diagnosis for a family with Ectodysplasin A (EDA) gene mutation as well as prenatal diagnosis, and report a novel EDA gene mutation.

METHODS

All coding sequences and flanking sequences of EDA gene were analyzed by Sanger sequencing in the proband, and then, according to EDA gene mutation in the proband, the EDA gene sequencing was performed on the family members. Based on the results above, the pathogenic mutation in EDA gene was finally identified, which was used for making prenatal diagnosis.

RESULTS

Sanger sequencing revealed c.302_303delCC [p.Pro101HisfsX11] mutation in EDA gene of the proband. This mutation induced EDA gene frame shift mutation which led to early termination of EDA gene translation because there was a termination codon TAA at the 11th codon behind the mutational site. Heterozygous deletion mutation (CC/--) at this locus was observed in the proband's mother and proband's grandmother, but the proband's aunt had no mutation at this locus. The analyses of amniotic fluid samples indicated negative sex-determining region on Y (SRY), and c.302_303delCC heterozygous deletion mutation.

CONCLUSION

We identified a pathogenetic mutation in EDA gene for the X-linked hypohidrotic ectodermal dysplasia family, made a prenatal diagnosis for the female carrier, and reported a novel EDA gene mutation.