Expanding the Mutational Spectrum of TSPEAR in Ectodermal Dysplasia Type 14: A Familial Case Study.

Background: Ectodermal dysplasia (ED) encompasses a heterogeneous group of genetic disorders affecting ectoderm-derived structures such as hair, teeth, nails, and sweat glands. Among these, variants in TSPEAR (Thrombospondin-type laminin G domain and epilepsy-associated repeats) have been implicated in autosomal recessive ED type 14 (OMIM 618180), predominantly manifesting with dental anomalies and hair dysplasia. However, the mutational spectrum of TSPEAR remains incompletely characterized.

Methods: Two female siblings (ID#1 and ID#4) were clinically evaluated for ED. Genetic analysis, including next-generation sequencing (NGS) and Sanger validation, was conducted to identify TSPEAR variants. A segregation study confirmed inheritance patterns within the family.

Results: Both affected siblings exhibited hallmark features of TSPEAR-related ED14, including oligodontia with dysmorphic, pointed maxillary central incisors. Hair thinning and cutaneous angiomas were predominant in ID#4. Genetic analysis identified two compound heterozygous variants in TSPEAR: c.543-1G>A, a splice-site variant likely to disrupt mRNA processing, and NM_144991.2:c.1251G>C(p.Gln417His), a missense variant with predicted deleterious effects. Segregation analysis confirmed maternal and paternal inheritance of the respective variants. A third sibling, ID#5, was identified as a heterozygous carrier without clinical manifestations.

Conclusions: This study contributes to the expanding understanding of TSPEAR-related ED14 by providing novel genotype-phenotype correlations.