We also report a novel amino acid substitution mutation in codon 192 of KRT2E (asparagine to lysine) in the conserved 1A helix initiation peptide of the protein in the patient with IBS.
We report a novel amino acid substitution mutation (asparagine-->aspartic acid) in codon 192 at the conserved 1A helix initiation site of the rod domain of KRT2E in a Japanese family with ichthyosis bullosa of Siemens.
The mutation resides within the 2B helix termination motif of the keratin 2e gene, and extends the body of evidence implicating keratin 2e gene mutations in IBS.
Mutations of the K2e gene involving five different residue positions (Q187P, T485P, L490P, E493D, E493K and E494K) are known to cause ichthyosis bullosa of Siemens.
Our results allow a differential diagnosis to be made between IBS and EHK at the genetic level and we suggest that patients diagnosed with EHK, but lacking keratin K1 or K10 mutations, should be re-examined for mutations in their K2e genes.