Close Linkage of the Genes for Rabbit IgA Allotypes, Af71 to Af75, to the Chromosomal Region Controlling Immunoglobulin Heavy Chain Allotypes

Five allotypes of rabbit IgA immunoglobulin, designated Af71, Af72, Af73, Af74 and Af75, have been identified in this laboratory and found to be inherited in linkage groups of f71 and f75, f72 and f74 or f73 and f74 as if they were controlled by three autosomal codominant alleles f71,75, f72,74 and f73,74, at a chromosomal region designated the f locus (1, 2).3 Tentatively, the f locus or region can be thought of as two linked regions or subloci such that one set of alleles controls f71, f72 and f73 and another set, controls f74 and f75. These five allotypic specificities are not found on IgG or IgM and thus appear to be associated uniquely with serum and secretory IgA (1). Furthermore, the phenogroup pair of allotypic specificities do not appear to be on the same IgA molecule but on separate IgA molecules, perhaps on subclasses of IgA (3).