Common and uncommon immunoglobulin haplotypes among Lebanese communities

Abstract

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.

The genetic diversity of three peculiar populations descending from the slave trade: Gm study of Noir Marron from French Guiana

“…Data on Gm allotypes of human immunoglobulins in African populations and other populations have been previously reported [16][17][18][19][20][21][22][23][24]. The Gm system has been frequently studied in human populations, due to its heterogeneous haplotype frequencies among populations [25][26][27], and is thus very useful to assess genetic relationships among populations in a given geographic area [28][29][30] or from different geographic areas [23,31,32]. Its high power of discrimination is relevant for the aims of this study.…”

Genetic Characterization and Origin of Tunisian Berbers

“…5* = 5,10,11. This haplotype is present in relatively low frequencies in the middle Orient [Lefranc et al, 1978] and in Tunisians [Lefranc et al, 1979] who could have received an or iental contribution through the founding of Carthage by the Phoenicians, through the Arab invasions, and through the long Turk Ottoman rule.…”

Multiple gene deletions within the human immunoglobulin heavy-chain cluster.

“…Selective absence of single IgG subclasses have been rarely identified by immunological testing for allo-and isotype determinants (12)(13)(14). Until now, the only cases of multiple IgCH gene deletions were found in apparently healthy individuals from highly inbred communities of Tunisian Berbers (23)(24)(25).…”

“…Selective deficiencies of Ig subclasses have occasionally been found, even in apparently healthy individuals (12)(13)(14). Two questions are raised by these findings: the first deals with the molecular basis of the lack of Ig chains, and the second is related to how and to what extent the lost effector functions are compensated.…”