Two Different Mutations in the Same Codon of a Type II Hair Keratin (hHb6) in Patients with Monilethrix

The study examined two unrelated patients with monilethrix, a genetic hair disorder, identifying two novel heterozygous point mutations in the same codon (402) of the hHb6 gene, which encodes a type II hair keratin. In patient A, a G to C transition resulted in a glutamine substitution (E402Q), while in patient B, a G to A transition led to a lysine substitution (E402K). These mutations were absent in unaffected relatives and 10 healthy controls, and disrupted a Taq I restriction site, confirmed via RFLP analysis. The research highlighted the role of hHb6 mutations in monilethrix and provided a diagnostic method for identifying these genetic changes, contributing to the understanding of keratin mutations affecting hair structure integrity.