Familial clustering and genetic background of primary biliary cirrhosis in Japan.

BACKGROUND: Primary biliary cirrhosis (PBC) is regarded as an autoimmune liver disease and familial clustering of PBC could represent some genetic predisposition to the disease. AIMS: To elucidate the genetic background of PBC by investigating familial cases of PBC.
METHODS: Familial cases were picked out from 171 PBC patients who enrolled in this study. We analyzed them and their family members, and compared them clinically and immunogenetically to non-familial cases.
RESULTS: Out of 171 PBC patients, ten (5.8%) were identified as familial PBC in five families. The clinical features of familial PBC were almost comparable to those of non-familial PBC. The distribution of human leukocyte antigens (HLA)-A, -B and -DR in familial PBC showed no specificity. Two new PBC patients were identified in one family in addition to the two originally enrolled PBC patients, resulting in four patients with PBC within the same family. The two new PBC patients had an identical HLA haplotype. On the other hand, one HLA-identical sister of a PBC patient in another family did not develop PBC.
CONCLUSIONS: Primary biliary cirrhosis can exhibit familial clustering without any HLA predisposition, however, a survey of families for PBC could be useful for identifying new patients with PBC in the asymptomatic stage for earlier diagnosis and treatment.