A newly identified missense mutation of the EDA1 gene in a Hungarian patient with Christ-Siemens-Touraine syndrome.

Christ-Siemens-Touraine syndrome (CST; OMIM 305100) belongs to the group of ectodermal dysplasias and is characterized by the development of sparse hair, abnormal or missing teeth and sweating deficiency. CST is the consequence of mutations located in the ectodysplasin A (EDA1) gene. We have identified a 35-year-old Hungarian man with characteristic dysmorphic facial features, sparse hair, reduced sweating and missing teeth. Direct sequencing of the coding regions revealed a novel missense mutation in the eighth exon (c.971T/A, p.Val324Glu). The affected patient carries the mutation in a hemizygous form. Previous studies reported the association of missense mutations with non-syndromic tooth agenesis. However, the reported hemizygous patient exhibits hypodontia as well as hypotrichosis and reduced sweating. His daughter, an obligate heterozygous carrier of the identified missense mutation, exhibits only mild teeth abnormalities. As the novel missense mutation is located within the tumor necrosis factor (TNF) domain of the ectodysplasin protein, we hypothesize that this genetic variant affects the ectodysplasin/NFκB signaling pathway.