The oligodontia phenotype in a X-linked hypohidrotic ectodermal dysplasia patient with a novel EVC2 variant

Objectives

To analyse the pathogenic genes in a patient with hypohidrotic ectodermal dysplasia (HED) and explore the relationship between pathogenic genes and the oligodontia phenotype.

Methods

Clinical data and peripheral blood were collected from a patient with HED. Pathogenic genes were analysed by whole-exon sequencing (WES) and verified by Singer sequencing. The secondary and tertiary structures of the variant proteins were predicted to analyse their toxicity.

Results

The patient exhibited a severe oligodontia phenotype, wherein only two deciduous canines were left in the upper jaw. WES revealed a hemizygous EDA variant c.466C > T p.(Arg156Cys) and a novel heterozygous EVC2 variant c.1772T > C p.(Leu591Ser). Prediction of the secondary and tertiary structures of the EDA variant p.(Arg156Cys) and EVC2 variant p.(Leu591Ser) indicated impaired function of both molecules.

Conclusion

The patient demonstrated a more severe oligodontia phenotype when compared with the other patients caused by the EDA variant c.466C > T. Since Evc2 is a positive regulator of the Sonic Hedgehog (Shh) signal pathway, we speculated that the EVC2 variant p.(Leu591Ser) may play a synergistic role in the oligodontia phenotype of HED, thereby exacerbating the oligodontia phenotype. Knowledge of oligodontia caused by multiple gene variants is of great significance for understanding individual differences in oligodontia phenotypes.

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.

The characterization of hypodontia, hypohidrosis, and hypotrichosis associated with X-linked hypohidrotic ectodermal dysplasia: A systematic review

The objective of this study was to review the published literature on X-linked hypohidrotic ectodermal dysplasia (XLHED) for the prevalence and characteristics of three features of XLHED: hypodontia, hypohidrosis, and hypotrichosis. A systematic search of English-language articles was conducted in May 2019 to identify publications with information on any of the three features of XLHED. We excluded studies with five or fewer participants, that did not specify X-linked inheritance or an EDA mutation, and discussed only management of features. The weighted means for total missing teeth, location of missing teeth, prevalence of reduced and absent sweating ability, and sparse or absent hair were analyzed across all studies. Additional findings for hypodontia, hypohidrosis, and hypotrichosis were summarized qualitatively. Twenty publications (18 studies) were accepted. Reported findings for males tended to be more informative than for carrier females. The weighted mean for missing teeth for affected males was 22.4 (range: 10-28) and carrier females was 3.4 (range: 0-22). The most common conserved teeth for males were the canines. The most common missing teeth for females were the maxillary lateral incisors. The weighted mean prevalence of reduced or absent sweating ability was 95.7% for males and 71.6% for females. The weighted mean prevalence for hypotrichosis was 88.1% for males and 61.6% for females. This systematic review provides insight into the prevalence, characteristics, and variability of the three classic features of XLHED. These findings provide detailed natural history information for families with XLHED as well as key characteristics that can aid in diagnosis.

Novel and Private EDA Mutations and Clinical Phenotypes of Korean Patients with X-Linked Hypohidrotic Ectodermal Dysplasia

X-linked hypohidrotic ectodermal dysplasia (XLHED; OMIM 305100) is the most common form of ectodermal dysplasia, presenting with the triad of hypotrichosis, hypodontia, and hypohidrosis. This disorder is caused by mutations in EDA, which encodes ectodysplasin A, a member of the tumor necrosis factor superfamily. In this study, we describe clinical and genetic characteristics of 10 Korean XLHED patients (9 males, 1 female) from 9 families. Nine out of the 10 patients manifested the cardinal triad of symptoms. Six patients had a positive family history, while 2 patients were brothers. The most common initial presentation was hypotrichosis or hypodontia, while 1 patient presented with recurrent high fever in early infancy. Sanger sequencing of the EDA gene was performed and revealed 9 different mutations. Three had been reported previously, and 6 were novel mutations. One female patient, carrying a previously reported missense mutation, might be affected by skewed X-inactivation. This is the first observational study investigating genetically confirmed XLHED patients in Korea. To provide appropriate supportive care and genetic counseling, clinicians should consider the possibility of XLHED in the differential diagnosis of recurrent fever in infants, as well as recognize the typical triad of symptoms.