Keratin 8 and 18 mutations are risk factors for developing liver disease of multiple etiologies

Keratin 8 and 18 (K8/K18) mutations are found in patients with cryptogenic cirrhosis, but the role of keratin mutations in noncryptogenic cirrhosis and the incidence of keratin mutations in the general population are not known. We screened for K8/K18 mutations in genomic DNA isolated from 314 liver explants of patients who primarily had noncryptogenic cirrhosis, and from 349 blood bank volunteers. Seven unique K8/K18 mutations were found in 11 independent patients with biliary atresia, hepatitis B/C, alcohol, primary biliary cirrhosis, and fulminant hepatitis. Seven of the 11 patients had mutations previously described in patients with cryptogenic cirrhosis: K8 Tyr-53 --> His, K8 Gly-61 --> Cys, and K18 His-127 --> Leu. The four remaining patients had mutations at one K8 and three other K18 new sites. Of the 349 blood bank control samples, only one contained the Tyr-53 His and one the Gly-61 --> Cys K8 mutations (P < 0.004 when comparing cirrhosis versus control groups). Two additional mutations were found in both the liver disease and blood bank groups and, hence, likely represent polymorphisms. Livers with keratin mutations had cytoplasmic filamentous deposits that were less frequent in livers without the mutations (P = 0.03). Therefore, K8/K18 are likely susceptibility genes for developing cryptogenic and noncryptogenic forms of liver disease.