Restriction fragment length polymorphisms associated with immunoglobulin heavy chain gamma genes in Tunisians.

DNA polymorphisms in the human immunoglobulin gamma (gamma) region have been studied in random Arabo-Berber Tunisians and in a large Tunisian Berber kindred. Haplotypes have then been designated, based on variation in the BamHI restriction fragments containing the C gamma 1, C gamma 2, C gamma 4, and C psi gamma genes. Two new haplotypes, in addition to the four previously described, have been observed. These new haplotypes, designated H5 and H6, were confirmed by family studies. The H5 haplotype was associated with black African Gm haplotypes (Gm1,17;..;5,6,11 and Gm1,17;..;5,11) (Gma,z;..;blc3bo and Gma,z;..;blbo) and probably represents a common haplotype in the black population. The haplotype H6 may be derived from H5. One of 39 random Tunisians was homozygous for a multigene deletion. DNA polymorphisms of the C gamma genes, in conjunction with Gm markers, provide highly variable genetic markers important for the characterization of human populations.