A novel variant causing X-linked hypohidrotic ectodermal dysplasia: Case report.

Hereditary ectodermal dysplasias are a complex group of inherited disorders characterised by abnormalities in two or more ectodermal derivatives (skin, nails, sweat glands, ). There are two main types of these disorders - hidrotic and hypohidrotic/anhidrotic ectodermal dysplasias. Hypohidrotic ectodermal dysplasia (HED) or Christ-Siemens-Touraine syndrome (OMIM: 305100) occurs in 1 out of 5000-10,000 births [19] and has an X-linked recessive inheritance pattern (X-linked hypohydrotic ectodermal dysplasia - XLHED) [2]. The main cause of XLHED is a broad range of pathogenic variants in the gene (HGNC:3157, Xq12-13) which encodes the transmembrane protein ectodysplasin-A [4]. We report here the case of a patient with a novel inherited allelic variant in the gene - NM_001399.5:c.337C>T (p.Gln113*) - in the heterozygous state. Targeted family member screening was conducted and other carriers of this gene pathogenic variant were identified and phenotypically characterised. The patient subsequently underwent fertilisation with preimplantation genetic testing for monogenic diseases (PGT-M).