Gm(x) in Negroes

The incidence of Gm allotypes in a group of Iraqi Arabs

Immunoglobulin allotypes were studied in a group of Iraqi Arabs. Results showed that the incidence of the Gm and Km markers investigated fall into the ranges quoted for Caucasian populations, except for the G3m(t) factor which was shown to have an incidence higher than that found in Caucasian groups.

Common and uncommon immunoglobulin haplotypes among Lebanese communities

Allotypes of IgG1, IgG2, IgG3, and IgA2 subclasses were investigated in seven Lebanese communities (three Moslem and four Christian). The Gm-Am haplotypes found were mainly those prevalent in Caucasians with a low frequency of haplotypes usually observed in Africans and Orientals. The difference between highlanders and lowlanders as expressed by G2m(23) was highly significant and suggested a possible adaptation to selective pressure related to the gamma2 genes, possibly due to endemic malaria in the past. Exceptional Gm-Am haplotypes were unambiguously determined by family studies. Some were characterized either by a deletion or a repression or, in contrast, by a partial or total duplication of gamma genes. Two others had uncommon combinations of allotypes: Gm17;23;5,10,11,13,14 A2m1, where G1m (17) was present without G1m (1); and Gm3;23;5,14 A2m1, where the CH3 allotypes G3m (10,11,13) were lacking.

Immunoglobulin haplotypes of two population groups in Iran

Genetic markers of IgG and IgA were investigated in two population groups from Iran. The Gm-Am haplotypes found were mainly those prevalent in Caucasians, with a low frequency of Asiatic haplotypes. Twenty samples had phenotypes that led to the assumption of rare haplotypes. The main ones were: Gm(z;n;b)a2m(1) and Gm(za;n;g)A2m(2). The first haplotype differs from the common haplotypes because G1m(z) is present instead of G1m(f), and the second because it has G2m(n) and A2m(2) in combination with G1m(za) and G3m(g).