Abstract
Genetic and environmental factors have been widely suggested to contribute to the pathogenesis of primary biliary cirrhosis (PBC), an autoimmune disease of unknown etiology leading to destruction of small bile ducts. Interestingly, epidemiologic data indicate a variable prevalence of the disease in different geographical areas. The study of clusters of PBC may provide clues as to possible triggers in the induction of immunopathology. We report herein four such unique PBC clusters that suggest the presence of both genetic and environmental factors in the induction of PBC. The first cluster is represented by a family of ten siblings of Palestinian origin that have an extraordinary frequency of PBC (with 5/8 sisters having the disease). Second, we describe the cases of a husband and wife, both having PBC. A family in which PBC was diagnosed in two genetically unrelated individuals, who lived in the same household, represents the third cluster. Fourth, we report a high prevalence of PBC cases in a very small area in Alaska. Although these data are anedoctal, the study of a large number of such clusters may provide a tool to estimate the roles of genetics and environment in the induction of autoimmunity.
Highlights
Primary biliary cirrhosis (PBC) is an autoimmune disease characterized by a female preponderance (9:1 female to male ratio) with most cases occurring between 40 and 60 years of age (Kaplan, 1996)
Epidemiological data seem conflicting in determining the importance of genetic versus environmental factors
While PBC prevalence seem to present a geographical distribution (Table I), suggesting a strong role for exogenous factors (Parikh-Patel et al, 1999), other data indicate a risk of developing the disease for a first-degree relative of an affected subject much higher compared to other autoimmune diseases, stressing a genetic susceptibility (Tsuji et al, 1999)
Summary
Genetic and environmental factors have been widely suggested to contribute to the pathogenesis of primary biliary cirrhosis (PBC), an autoimmune disease of unknown etiology leading to destruction of small bile ducts. We report four such unique PBC clusters that suggest the presence of both genetic and environmental factors in the induction of PBC. The first cluster is represented by a family of ten siblings of Palestinian origin that have an extraordinary frequency of PBC (with 5/8 sisters having the disease). We report a high prevalence of PBC cases in a very small area in Alaska. These data are anedoctal, the study of a large number of such clusters may provide a tool to estimate the roles of genetics and environment in the induction of autoimmunity
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