Am(1), the first genetic marker of human immunoglobulin A.

The genetic markers of human immunoglobulins have significantly contributed to the understanding of the molecular biology of antibody synthesis. Like the Gm markers of IgG, the first genetic marker of serum IgA, a major immunoglubulin of exocrine secretions, has now been defined and termed Am(1). It is inherited as a Mendelian dominant trait and is independent of the Gm and Inv allotypes. Am(1) is localized in the alpha-chains of the gammaA(2) subclass and is independent of the serum gammaA(2) levels. Its polymorphism makes it suitable for studies in population genetics and the molecular biology of IgA globulin.