Abstract
C4 deficient (C4D) guinea pigs have a deficiency in C4 synthesis that appears to be due to a structural gene defect. Previous work has demonstrated that inheritance of this defect follows simple Mendelian laws. This report demonstrates linkage between C4D and an antigen controlled by a gene in the major histocompatibility complex of the guinea pig. Recent studies have defined a major histocompatibility locus (MHL) in the guinea pig (B) which appears to be equivalent to the D or K loci in the mouse, as well as a second region which resembles the mouse Ia. Four alleles of the B locus have been identified: B.1, B.2, B.3, B.4. Preliminary screening of the NIH multipurpose colony (the colony in which C4D was first observed) showed that 5 to 10% of the animals were homozygous for the B.1 antigen; the remaining animals had detectable B.3 antigen by serologic testing.
