Lack of an autosomal recessive genetic influence in vertical transmission of hepatitis B antigen

Abstract

BLUMBERG et al. have postulated that predisposition to the hepatitis B antigen (HBsAg) carrier state is inherited as an autosomal recessive gene¹. Crucial to this concept, but lacking in Blumberg's populations, are families in which both parents are carriers. All offspring of such families should be homozygous for carrier predisposition and once infected all should become carriers. To test Blumberg's hypothesis, we compared rates of hepatitis B antigenaemia among children in two groups of families: those in which both parents were HBsAg carriers and those in which the mother was a carrier, but the father's serum was antibody (anti-HBs) positive. We did not include families when the father's serum was both HBsAg and anti-HBs negative, since carrier state predisposition remained unknown without evidence of previous hepatitis B virus (HBV) infection. If the autosomal recessive genetic hypothesis is correct, we would expect, in families with two HBsAg carrier parents, that all HBV-infected offspring would become carriers. In contrast, only a small proportion of children would become carriers in families with a carrier mother and an antibody-positive father, since most children would have only a single gene for carrier predisposition (inherited from their mothers) and would, like their fathers, form antibody after exposure rather than becoming carriers.