A usual frameshift and delayed termination codon mutation in keratin 5 causes a novel type of epidermolysis bullosa simplex with migratory circinate erythema.
We report here two unrelated families in Japan and Korea having patients with a unique type of epidermolysis bullosa simplex and a novel mutation in the keratin gene KRT5, i.e., a frameshift and delayed stop codon inconsistent with any subtype described before. The patients showed migratory circinate erythema and multiple vesicles on the circular belt-like areas affected by erythema. Electron microscopy of skin biopsies showed a reduction in the number of keratin intermediate filaments in the basal cells without tonofilament clumping. We identified a novel heterozygous deletion mutation (1649delG of KRT5) in both cases. This deletion is predicted to produce a mutant keratin 5 protein with a frameshift of its terminal 41 amino acids and 35 amino acids longer than the wild-type keratin 5 protein due to a delayed termination codon. As the same abnormal elongated mutant KRT5 gene was found in the independent families, the predicted abnormal elongated keratin protein is likely to lead to an atypical clinical phenotype that has never been reported, possibly by interfering with the functional interaction between keratin and its associated proteins.
Gu
Li-Hong
LH
Department of Dermatology, Gifu University School of Medicine, Tsukasa-Machi 40, Gifu 500-8705, Japan.
Kim
Soo-Chan
SC
Ichiki
Yoshiro
Y
Park
Junsu
J
Nagai
Miki
M
Kitajima
Yasuo
Y
D000595:Amino Acid Sequence; D002675:Child, Preschool; D018388:Codon, Terminator / Q000235:genetics; D016110:Epidermolysis Bullosa Simplex / Q000235:genetics* / Q000473:pathology; D004890:Erythema / Q000235:genetics / Q000473:pathology; D005260:Female; D016368:Frameshift Mutation; D017353:Gene Deletion; D006579:Heterozygote; D006801:Humans; D007223:Infant; D053555:Keratin-5; D007633:Keratins / Q000235:genetics*; D008969:Molecular Sequence Data; D010641:Phenotype
D018388:Codon, Terminator; C503940:KRT5 protein, human; D053555:Keratin-5; D007633:Keratins