Keratin 8 Y54H and G62C mutations are not associated with inflammatory bowel disease

Background. Keratin 8 is a major component of intermediate filaments in single-layered epithelia of the gastrointestinal tract. Keratin 8 deficient mice display signs of colitis and diarrhoea characteristic for inflammatory bowel disease. Very recently, two keratin 8 mutations, Y54H and G62C, were identified. Aims. We investigated if these keratin 8 missense mutations were associated with inflammatory bowel disease. Patients. In total, 217 German patients with Crohn's disease, 131 German patients with ulcerative colitis, and 560 German control subjects were enrolled in this study. Methods. Samples were analysed by PCR amplification and subsequent melting curve analysis using fluorescence resonance energy transfer probes. Results. The G62C mutation was detected in five (2.3%) patients presenting with Crohn's disease and in three (2.3%) with ulcerative colitis. In comparison, 9 (1.6%) out of 560 controls were heterozygous for this mutation. No patient or control was homozygous for this mutation. Patients carrying one mutant allele did not show any noticeable characteristics in their corresponding phenotype. In contrast, the Y54H mutation was observed in neither any of the 348 patients with inflammatory bowel disease nor in any control subject. Conclusions. Our data indicate that both keratin 8 mutations, G62C and Y54H, do not play a relevant pathogenic role in inflammatory bowel disease.