Background About 10 percent of patients who undergo liver transplantationhave cryptogenic liver disease. In animal models, the absenceof heteropolymeric keratins 8 and 18 or the presence of mutantkeratins in hepatocytes causes or promotes liver disease. Wehave previously described a mutation in the keratin 18 genein a patient with cryptogenic cirrhosis, but the importanceof mutations in the keratin 8 and keratin 18 genes in such patientsis unclear.
Methods We tested for mutations in the keratin 8 and keratin18 genes in purified genomic DNA isolated from 150 explantedlivers and 89 peripheral-blood specimens from three groups ofpatients: 55 patients with cryptogenic liver disease; 98 patientswith noncryptogenic liver disease, with causes that includedalcohol use, autoimmunity, drug use, and viral infections; and86 randomly selected inpatients and outpatients who providedblood to the hematology laboratory.
Results Of the 55 patients with cryptogenic liver disease, 3had glycine-to-cysteine mutations at position 61 (a highly conservedglycine) of keratin 8, and 2 had tyrosine-to-histidine mutationsat position 53 of keratin 8. These mutations were not detectedin the patients with other liver diseases or in the randomlyselected patients. In transfected cells, the glycine-to-cysteinemutation limited keratin-filament reorganization when the cellswere exposed to oxidative stress. In contrast, the tyrosine-to-histidinemutation destabilized keratin filaments when transfected cellswere exposed to heat or okadaic acid stress.
Conclusions Mutations in the keratin 8 gene may predispose peopleto liver disease and may account for cryptogenic liver diseasein some patients.
Source Information
From the Gastroenterology Section, Palo Alto Veterans Affairs Medical Center and Stanford University School of Medicine, Palo Alto, Calif. (N.-O.K., M.B.O.); the Department of Transplantation, California Pacific Medical Center, San Francisco (R.G.); and the Gastroenterology Section, San Francisco Veterans Affairs Medical Center, San Francisco (T.L.W.).
Address reprint requests to Dr. Ku at the Palo Alto Veterans Affairs Medical Center, Mail Code 154J, 3801 Miranda Ave., Palo Alto, CA 94304.
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