Clinical and Molecular Genetic Analysis of Cases with Ectodermal Dysplasia

Introduction: Ectodermal dysplasias are a group of >200 clinically and congenitally heterogeneous disorders characterized by abnormal development in the ectodermal structures, such as hair, nails, teeth, and sweat glands. We report here the clinical and molecular genetic analysis of five Greek families with different types of ectodermal dysplasia (ED).

Subjects: The study involved 15 individuals from 5 Greek families that included 8 ED patients, 5 carriers of recessive X-linked or autosomal ED, and 2 healthy relatives. After genetic counseling, the parents signed an informed consent form before subsequent genetic testing.

Methods: Genomic DNA was isolated from white blood cells of all studied individuals. The search for mutations was realized in patients' DNA samples using next-generation sequencing (NGS) gene panel, whole exome sequencing (WES), chromosomal microarray analysis (CMA), and multiplex ligation-dependent probe amplification (MLPA) technique.

Results: The clinical diagnosis of common X-linked recessive hypohidrotic ectodermal dysplasia (HED) was suspected in five male patients with partial anodontia of baby and permanent teeth, hypohidrosis, and thin hair from three families. All HED patients were hemizygous for deletions in the EDA1 gene (Xq13.1): three related patients had a 20 bp deletion, one had a 19 bp deletion, and one had a 180 bp deletion. A female patient had the rare autosomal dominant syndrome of ankyloblepharon-ectodermal dysplasia-cleft lip/palate (AEC) caused by heterozygous missense mutation in the TP63 gene (3q28) that appeared de novo. Two siblings with hypotrichosis and hypodontia, a female and a male, had two pathogenic mutations in compound heterozygosity in the TSPEAR gene (21q22.3); therefore they presented with ectodermal dysplasia type 14 (ECTD14).

Conclusion: Clinical and molecular genetic analysis may set an accurate diagnosis of different types of ED. In the reported families, genetic diagnosis and genetic counselling assisted the parents to view their children's condition realistically and to cooperate with the specialists who will contribute to the best possible treatment for their children.