Mutations in the Keratin 85 (KRT85/hHb5) Gene Underlie Pure Hair and Nail Ectodermal Dysplasia

Researchers identified two distinct homozygous mutations in the KRT85 gene in two consanguineous Pakistani families with pure hair and nail ectodermal dysplasia (PHNED), a congenital disorder characterized by hypotrichosis and nail dystrophy. Family A exhibited a deletion mutation (c.1448_1449delCT) leading to a frameshift and premature termination, while Family B had a G-to-A substitution (c.233G>A) resulting in an arginine to histidine transition. The study suggested that these mutations disrupt the function of the K85 protein, crucial for keratinization in hair and nails, leading to the observed phenotypes. The findings expanded the spectrum of known KRT85 mutations and highlighted the importance of K85 in maintaining hair and nail integrity.