Different Alleles Cause an Imbalance in A₂ and A₂B Phenotypes of the ABO Blood Group

Abstract

*R101 is presumably expressed as phenotype A1 in *R101/*O heterozygous individuals, but as phenotype A2 in *R101/*B heterozygotes, thus giving rise to a high A2B phenotype frequency.

Molecular basis of the A2B in Taiwan

“…This observation is similar to some other populations including AfricanAmerican and Oriental populations [18,19,26,27]. The genotypes of the A 2 B phenotype could be heterozygotes of cis-AB/O or B allele or heterozygote of A 2 /B allele.…”

“…The genotypes of the A 2 B phenotype could be heterozygotes of cis-AB/O or B allele or heterozygote of A 2 /B allele. Since Yamamoto et al first reported the genotype of A 2 allele (A201) [13], currently nine A 2 and four cis-AB genotypes have been identified [3,6,[13][14][15][16][17][18][19][20][21][22][23]. However, due to the very low frequencies of the A 2 subgroup in Taiwan, only one A 2 (A207) and two cis-AB (cis-AB01, cis-AB04) genotypes have been reported in Taiwan up to the present [15,22].…”

“…Currently, according to the nomenclature defined by the blood group antigen gene mutation database (BGMUT, http://www.ncbi.nlm.nih.gov/ projects/mhc/xslcgi.fcgi? cmd = bgmut) there are nine A 2 genotypes known, which are A201 (nt 467C [ T; 1061del [3,6,[13][14][15][16][17][18]. The A 2 alleles in various populations around the world are caused by different and specific genotypes, such as A201 in Caucasians, A202, A203, A204 in Japanese and A102, A204 in Koreans [3,18,19].…”

“…cmd = bgmut) there are nine A 2 genotypes known, which are A201 (nt 467C [ T; 1061del [3,6,[13][14][15][16][17][18]. The A 2 alleles in various populations around the world are caused by different and specific genotypes, such as A201 in Caucasians, A202, A203, A204 in Japanese and A102, A204 in Koreans [3,18,19]. The A 2 B phenotype is a subtype of the blood group AB and is distinguished from the AB phenotype by the absence of red cell agglutination with anti-A 1 lectin (Dolichos biflorus).Some of A 2 B phenotypes may be caused by the cis-AB genotype.…”

Genetic Analysis of ABO and Rh Blood Groups in Backward Caste Population of Uttar Pradesh, India

“…Four nucleotide substitutions are translated into different amino acid substitution. It has made it possible to analyze genetically ABO blood group antigens using molecular biology techniques (Larsen et al, 1990;Hasoi et al, 1998;Ogasaware et al, 1996Ogasaware et al, , 1998Yamamoto et al, 1990). The antigens A, B, and their variants result from functional glycosyltransferase genes capable of transferring N-acetyl-D-galactosamine or D-galactose or both to the nonreducing ends of suitable oligosaccharide chains found on red cell membrane glycoproteins and glycolipids.…”