Md. Mcginnis et al., ANCIENT, HIGHLY POLYMORPHIC HUMAN MAJOR HISTOCOMPATIBILITY COMPLEX DQA1 INTRON SEQUENCES, American journal of medical genetics, 52(4), 1994, pp. 438-444
A 438 basepair intron 1 sequence adjacent to exon 2 in the human major
histocompatibility complex DQA1 gene defined 16 allelic variants in 6
9 individuals from wide ethnic backgrounds. In contrast, the most vari
able coding region spanned by the 247 basepair exon 2 defined 11 allel
ic variants. Our phylogenetic human intron 1 tree derived by the Boots
trap algorithm reflects the same relative allelic relationships as the
reported DQA1 exon 2 tree [Gyllensten and Erlich, Hum Immunol 36:1-10
, 1989]. Thus 3' DQA1 intron 1 and exon 2 have cosegregated since dive
rgence of the human races. Comparison of human alleles to a Rhesus mon
key DQA1 first intron sequence found only 10 nucleotide substitutions
unique to Rhesus, with the other 428 positions (98%) found in at least
one human allele. This high degree of homology reflects the evolution
ary stability of intron sequences since these two species diverged ove
r 20 million years ago. Because more intron 1 alleles exist than exon
2 alleles, these polymorphic introns can be used to improve tissue typ
ing for transplantation, paternity testing, and forensics and to deriv
e more complete phylogenetic trees. These results suggest that introns
represent a previously underutilized polymorphic resource. (C) 1994 W
iley-Liss, Inc.