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

Identification of six novel mutations in EDA from 20 hypohidrotic ectodermal dysplasia families

OBJECTIVE

To investigate the genetic causes of 22 patients with clinically high suspicion of X-linked hypohidrotic ectodermal dysplasia from 20 unrelated Chinese families, expand the spectrum of ectodysplasin-A mutations, and provide more evidence for variants of uncertain significance.

SUBJECTS AND METHODS

Whole-exome sequencing was performed and potentially pathogenic variants were verified by Sanger sequencing. Western blotting, real-time PCR and immunofluorescence analyses were performed to investigate the preliminary functions of the candidate variants.

RESULTS

Nineteen ectodysplasin-A variants were identified, six of which were not previously reported. Among these variants, we identified a patient who carried two mutations in ectodysplasin-A and exhibited more severe phenotypes. Additionally, mutant protein expression levels decreased, whereas mRNA transcription levels increased. Cellular sublocalisation of the variants located in the tumour necrosis factor homologous domain showed that the proteins accumulated in the nucleus, whereas wild-type proteins remained in the cell membrane. A rare indel variant and two classical splicing variants that lead to exon 7 skipping were detected.

CONCLUSIONS

This study provides definitive diagnoses for 20 families with suspected X-linked hypohidrotic ectodermal dysplasia and additional information on clinical heterogeneity and genotype-phenotype relationships.

Eight EDA mutations in Chinese patients with tooth agenesis and genotype-phenotype analysis

OBJECTIVE

Tooth agenesis is a common craniofacial malformation, which is often associated with gene mutations. The purpose of this research was to investigate and uncover ectodysplasin A (EDA) gene variants in eight Chinese families affected with tooth agenesis.

METHODS

Genomic DNA was extracted from tooth agenesis families and sequenced using whole-exome sequencing. The expression of ectodysplasin A1 (EDA1) protein was studied by western blot, binding activity with receptor was tested by pull-down and the NF-κB transcriptional activity was analyzed by Dual luciferase assay.

RESULTS

Eight EDA missense variants were discovered, of which two (c.T812C, c.A1073G) were novel. The bioinformatics analysis indicated that these variants might be pathogenic. The tertiary structure analysis revealed that these eight variants could cause structural damage to EDA proteins. In vitro functional studies demonstrated that the variants greatly affect protein stability or impair the EDA-EDAR interaction; thereby significantly affecting the downstream NF-κb transcriptional activity. In addition, we summarized the genotype-phenotype correlation caused by EDA variants and found that EDA mutations leading to NSTA are mostly missense mutations located in the TNF domain.

CONCLUSION

Our results broaden the variant spectrum of the EDA gene associated with tooth agenesis and provide valuable information for future genetic counseling.

A Novel Ectodysplasin a Gene mutation of X-Linked Hypohidrotic Ectodermal Dysplasia

Introduction

Hypohidrotic ectodermal dysplasia (HED) is a genetic disorder that influences structures of ectodermal origin, such as teeth, hair, and sweat glands. Compared with autosomal recessive and dominant modes of inheritance, the X-linked HED (XLHED) characterized by Hypodontia/Oligodontia teeth, Absent/sparse hair, Anhidrosis/hypohidrosis, and characteristic facial features, is the most frequent and its primary cause is the mutation of ectodysplasin A (EDA) gene. This research aimed to expound the clinical and molecular features of a Chinese male with XLHED and to summarize and compare several previous findings.

Methods

Genomic DNA was obtained from the peripheral blood of the proband and his family members, then Sanger sequencing was used to perform a mutational analysis of EDA. Real-time quantitative PCR and Western blotting were used to detect EDA expression. The transcriptional activity of NF-κB was detected using a luciferase assay.

Results

The probandwith XLHED was identified a novel EDA mutation, c.1119G>C(p.M373I), that affected the molecular analysis of transmembrane protein exon8 mutations, inherited from the mother. He showed a severe multiple-tooth loss, with over 20 permanent teeth missing and sparse hair and eyebrows, dry, thin, and itching skin. Furthermore, his sweating function was abnormal to a certain extent.

Discussion

The functional study showed that this novel mutant led to a significant decrease in the EDA expression level and transcriptional activity of NF-κB. Our findings extend the range of EDA mutations in XLHED patients, which provides the basis and idea for further exploring the pathogenesis of XLHED.

Rare Pediatric Genetic Case Report of X-linked Hypohidrotic Ectodermal Dysplasia Type 1

Ectodermal dysplasia (ED) is a rare disorder that appears differently in clinical cases and can present with a variety of combinations and severities of abnormalities that can involve a variety of tissues. The disease might appear clinically as hypotrichosis, hypohidrosis, or hypodontia, among other clinical manifestations. The patient, a five-year-old boy, was seen at the Taibah University Dental Clinic and was diagnosed with X-linked hypohidrotic ectodermal dysplasia type 1 based on clinical radiographic and genetic findings. Although there is no base data for reporting this case, the present case presentation could alert dental practitioners and expand scientific database knowledge on the dental and/or oral characteristics of this abnormality.

Expanding the genetic spectrum of tooth agenesis using whole-exome sequencing

BACKGROUND

Tooth agenesis is a high genetic heterogeneous disorder with more than eighty genes identified as associated molecular causes. The present study aimed to detect the possible pathogenic variants in a cohort of well-characterized probands with a clinical diagnosis of tooth agenesis.

METHODS

We performed whole-exome sequencing (WES) in 131 tooth agenesis patients with no previously identified molecular diagnosis. All the potential pathogenic variants were verified by Sanger sequencing in patients and their family members. Results Seventy-three patients were genetically diagnosed in 131 unrelated Chinese patients with tooth agenesis, providing a positive molecular diagnostic rate of 55.7%, including 53.8% (49/91) in the non-syndromic tooth agenesis (NSTA) group, and 60.0% (24/40) in syndromic tooth agenesis (STA) group. A total of 75 variants from 13 different genes were identified, including 33 novel variants, and WNT10A and EDA are the most common causative genes associated with non-syndromic and syndromic tooth agenesis, respectively.

CONCLUSIONS

This study further extends the variant spectrum and clinical profiles of tooth agenesis, which has a positive significance for clinical practice, genetic diagnosis, prenatal counseling and future treatment.

Ectodysplasin A (EDA) Signaling: From Skin Appendage to Multiple Diseases

Ectodysplasin A (EDA) signaling is initially identified as morphogenic signaling regulating the formation of skin appendages including teeth, hair follicles, exocrine glands in mammals, feathers in birds and scales in fish. Gene mutation in EDA signaling causes hypohidrotic ectodermal dysplasia (HED), a congenital hereditary disease with malformation of skin appendages. Interestingly, emerging evidence suggests that EDA and its receptors can modulate the proliferation, apoptosis, differentiation and migration of cancer cells, and thus may regulate tumorigenesis and cancer progression. More recently, as a newly discovered hepatocyte factor, EDA pathway has been demonstrated to be involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and type II diabetes by regulating glucose and lipid metabolism. In this review, we summarize the function of EDA signaling from skin appendage development to multiple other diseases, and discuss the clinical application of recombinant EDA protein as well as other potential targets for disease intervention.