A SINE insertion provides information on the divergence of the HLA-DQA1 and HLA-DQA2 genes.
The class II region of the human major histocompatibility complex (MHC) contains a cluster of highly polymorphic genes organized into at least three subloci (DR, DQ, and DP), each encoding a subset of surface antigens participating in the modulation of the immune response. Genetic diversity in this system is brought about by two major mechanisms, hypermutation and trans-species evolution. The DQ subregion contains a pair of closely related A genes, HLA-DQA1 and HLA-DQA2, whose phylogenetic relationship is uncertain, although their generation by duplication of an ancestral A gene before or after speciation can be implied. We report here the presence of a member of the Alu repetitive family immediately 5' to the HLA-DQA1 gene. The sequence of this element indicates that it may have integrated by transposition at the time of divergence of hominoids from Old World monkeys. HLA-DQA2 carries an empty integration target site in place of the Alu, thereby suggesting that the insertion of Alu near HLA-DQA1 was preceded by the separation of the two genes.
Del Pozzo
G
G
International Institute of Genetics and Biophysics, CNR, Napoli, Italy.
Guardiola
J
J
D000818:Animals; D005075:Biological Evolution; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D015870:Gene Expression; D014644:Genetic Variation; D006683:HLA-DQ Antigens / Q000235:genetics*; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid
D004251:DNA Transposable Elements; D006683:HLA-DQ Antigens; D000949:Histocompatibility Antigens Class II