Technical Report No. 22-88
Imbalance of blood group A subtypes and the existence of superactive B* gene in Hiroshima and Nagasaki
Hamilton HB, Yoshida A, Dave VEditor’s note: A publication based on this report was published in Am J Hum Genet 43:422-8, 1988.
Summary
Blood type A can be classified into subgroups A1, A2, and A1 -A2 intermediate (Aint) on the basis of serological criteria. An excess of A2B over A2, noted in some black populations and among the Japanese, though not in Caucasoids, is inconsistent with the classical Mendelian mode of inheritance of the allelic A1 and A2 genes. Characterization of the enzymatic properties of blood group A and B enzymes in the serum has shown that serological type A2B blood of some blacks contains A1 enzyme and a superactive B* enzyme. An excess of A2B found in a study of more than 15,000 residents of Hiroshima and Nagasaki prompted investigation of the characteristics of the A and B enzymes in 60 blood samples, 37 from individuals in 13 unrelated families and 23 from other unrelated individuals in the two cities. Among 29 samples unequivocally typed serologically as A2B, 15 were confirmed as A2B enzymatically; 9 contained A1 and B* enzymes, not A2 or B enzymes, thus being A1B*; 2 contained Aint and B* enzymes, thus being AintB; results from the remaining 3 were ambiguous. Hiroshima differs from Nagasaki in the frequency of the A2B serological type and also in the occurrence of the B* enzyme, Nagasaki having a higher proportion of both. Judging from those cases where a family study was possible, the transmission of the B* enzyme appears to be compatible with the Mendelian mode of inheritance. The excess of serological A2B in the Japanese appears to be ascribable, at least in part, to the relatively high frequency of a B* gene.
Family studies on probands with chromosome abnormalities revealed that the majority of cases (about 90%) with autosomal structural rearrangements of the balanced type were inherited from one or the other parent. The mutation rates for these rearrangements were similar between the exposed and control groups, being 0.98 x 10-4 per gamete per generation.
Blood type A can be classified into subgroups A1, A2, and A1 -A2 intermediate (Aint) on the basis of serological criteria. An excess of A2B over A2, noted in some black populations and among the Japanese, though not in Caucasoids, is inconsistent with the classical Mendelian mode of inheritance of the allelic A1 and A2 genes. Characterization of the enzymatic properties of blood group A and B enzymes in the serum has shown that serological type A2B blood of some blacks contains A1 enzyme and a superactive B* enzyme. An excess of A2B found in a study of more than 15,000 residents of Hiroshima and Nagasaki prompted investigation of the characteristics of the A and B enzymes in 60 blood samples, 37 from individuals in 13 unrelated families and 23 from other unrelated individuals in the two cities. Among 29 samples unequivocally typed serologically as A2B, 15 were confirmed as A2B enzymatically; 9 contained A1 and B* enzymes, not A2 or B enzymes, thus being A1B*; 2 contained Aint and B* enzymes, thus being AintB; results from the remaining 3 were ambiguous. Hiroshima differs from Nagasaki in the frequency of the A2B serological type and also in the occurrence of the B* enzyme, Nagasaki having a higher proportion of both. Judging from those cases where a family study was possible, the transmission of the B* enzyme appears to be compatible with the Mendelian mode of inheritance. The excess of serological A2B in the Japanese appears to be ascribable, at least in part, to the relatively high frequency of a B* gene.
Family studies on probands with chromosome abnormalities revealed that the majority of cases (about 90%) with autosomal structural rearrangements of the balanced type were inherited from one or the other parent. The mutation rates for these rearrangements were similar between the exposed and control groups, being 0.98 x 10-4 per gamete per generation.