A novel EDA1 missense mutation in X-linked hypohidrotic ectodermal dysplasia

Abstract

A mutation in the epithelial morphogen gene ectodysplasin-A1 (EDA1) is responsible for the disorder X-linked hypohidrotic ectodermal dysplasia (XLHED), the most common form of ectodermal dysplasia. XLHED is characterized by impaired development of hair, eccrine sweat glands, and teeth. This study aimed to identify potentially pathogenic mutations in four Chinese XLHED families.Genomic DNA was extracted from the peripheral blood and sequenced. Sanger sequencing was used to carry out mutational analysis of the EDA1 gene, and the three-dimensional structure of the novel mutant residues in the EDA trimer was determined. Transcriptional activity of NF-κB was tested by Dual luciferin assay.We identified a novel EDA1 mutation (c.1046C>T) and detected 3 other previously-reported mutations (c.146T>A; c.457C>T; c.467G>A). Our findings demonstrated that novel mutation c.1046C>T (p.A349 V) resulted in XLHED. The novel mutation could cause volume repulsion in the protein due to enlargement of the amino acid side chain. Dual luciferase assay revealed that transcriptional NF-κB activation induced by XLHED EDA1 protein was significantly reduced compared with wild-type EDA1.These results extend the spectrum of EDA1 mutations in XLHED patients and suggest a functional role of the novel mutation in XLHED.

Figure 1

Characteristics of individuals with hypohidrotic ectodermal dysplasia (HED). (A) Positive image of probands; (B) Intraoral image of probands; (C) Legend of intraoral missing teeth of probands; (D) Panoramic radiography of probands.

Figure 2

Sequencing results show EDA1 mutations in four families. The four probands, affected with HED, were found to have missense mutation: (A) Patient 1: EDA1 c.1046 C>T; (B) Patient 2: EDA1 c. 146 T>A; (C) Patient 3: EDA1 c.457 C>T; (D) Patient 4: EDA1 c.467 G>A. Mothers of patient are all heterozygotes, fathers are all unaffected.

Figure 3

Protein structure of 3 monomers showing the conserved locations of the mutant sites in the EDA protein sequence. (A) Top view of the trimer of EDA; (B) side view of the trimer of EDA; (C) Sequence alignment results show that the four residues are conserved across five species: the mutant allele is boxed.

Figure 4

Effect of XLHED-EDA1 mutation on the transcriptional activation of NF-κB by dual luciferase assay. It shows that transcriptional NF-κB activation induced by mutant EDA1 protein (A349 V) was significantly reduced compared to wild-type EDA1. ^∗P < .01; ^∗∗P < .001; Wt: wild-type.