Mild Recessive Bullous Congenital Ichthyosiform Erythroderma due to a Previously Unidentified Homozygous Keratin 10 Nonsense Mutation

We have identified a previously unreported homozygous nonsense mutation p.Cys427X in the keratin 10 (K10) gene (KRT10) in a Turkish girl with recessive bullous congenital ichthyosiform erythroderma (BCIE) showing superficial blistering. p.Cys427X is located upstream of the previously reported homozygous truncation mutation within the same exon 6 causing mRNA decay. Immunohistochemical examination showed a complete absence of K10 protein in the patient's epidermis. The findings of this study suggest that K10 knockout patients show unique clinicopathological features of clinically mild BCIE with blisters occurring within the granular layer. In addition, the unaffected, heterozygous carriers of the mutation indicate that the K10 peptide from one normal allele alone is sufficient for keratin network formation.