Cholestasis, Benign Recurrent Intrahepatic, 2

A number sign (#) is used with this entry because benign recurrent intrahepatic cholestasis-2 (BRIC2) is caused by mutation in the ABCB11 gene (603201), also known as the bile salt export pump (BSEP), on chromosome 2q31.

For a discussion of genetic heterogeneity of BRIC, see 243300.

Description

Benign recurrent intrahepatic cholestasis is characterized by intermittent episodes of cholestasis without progression to liver failure. The cholestatic attacks vary in severity and duration and patients are asymptomatic between episodes, both clinically and biochemically (van Mil et al., 2004).

Clinical Features

Van Mil et al. (2004) reported clinical features of 11 patients from 8 families with BRIC2 confirmed by genetic analysis. Inheritance followed an autosomal recessive pattern. Age at onset ranged from 2 months to 24 years. The most common features were hepatosplenomegaly and cholelithiasis. In general, liver biopsies showed cholestasis without fibrosis, although mild fibrosis was seen in some patients. Cholestasis sometimes was associated with swelling and degeneration of hepatocytes. Serum bile acids were increased during episodes. Patients in 3 families developed permanent cholestasis later in life. Precipitating factors included viral infections and pregnancy.

Noe et al. (2005) reported a 16-year-old boy who presented with a history of intermittent episodes of pruritus and steatorrhea for several years. Cholestatic episodes were reportedly triggered by infections or intake of certain medications. Laboratory studies showed increased serum alkaline phosphatase and bilirubin with normal gamma-GGT (612346). Liver biopsy showed mild hepatocellular and canalicular cholestasis without portal fibrosis. Immunohistochemical studies showed expression of the BSEP protein in the canalicular membrane of hepatocytes.

Molecular Genetics

Van Mil et al. (2004) identified 8 different mutations in the ABCB11 gene (see, e.g., 603201.0002) in 11 patients from 8 families with BRIC2. Homozygous and compound heterozygous mutations were identified in 7 patients and 3 patients, respectively. One patient had only a heterozygous mutation.

In a 16-year-old boy with BRIC2, Noe et al. (2005) identified compound heterozygosity for 2 mutations in the ABCB11 gene (603201.0002; 603201.0006). Each unaffected parent was heterozygous for 1 of the mutations. In vitro functional expression studies showed that the mutant proteins retained residual activity.