Familial clustering of hepatitis B antigen: a study in relatives of patients with liver diseases and hepatitis B antigenaemia.

Twelve of the 100 family contacts of 29 patients with transient and persistent hepatitis B antigenaemia were found to be positive for hepatitis B antigen (HBAg). No relation was found between familial clustering and the nature of liver disease or the duration of antigenaemia in the index cases.Eight affected relatives were apparently healthy carriers of HBAG, one had cirrhosis, and three (in the same family) developed acute viral hepatitis.The absence of parenteral exposure in the HBA,-positive family contacts and the identity in antigenic determinants d or y with those of the index cases, suggest a non-parenteral spread of HBAg in families of patients with HBAg-associated liver diseases.