Inherited Differences in Blood Group A Subtypes in Caucasians and Negroes

Grundbacher, F. J.; Dj, Summerlin

doi:10.1159/000152389

Cited by 8 publications

(15 citation statements)

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“…In this test, therefore, A2 and Aint cannot be subdivided. According to Grundbacher and Summerlin [6], the A subtypes are defined as follows: A| and Aint: agglutination with equal volume of 8-fold or higher dilution of the Anti-A| lectin after 1 h at 25 °C, and A2: no aggluti nation with equal volume of 8-fold dilu tion of the lectin after 1 h at 25 °C. In their method, A| and Aint are distinguished based on their agglutinability with Ulex anti-H lectin.…”

Section: Blood Types Determined By the Agglutination Testmentioning

confidence: 99%

“…Their kinetic properties are: A|-enzyme: high activity in plasma, pH optima at pH 6 (pH 6/pH 8> 1.3), high affinity to UDPGalNAc (high/low~ 1.15) and 2'-fucosyllactose [3][4][5]; A2-enzyme: low activity in plasma, pH optima at pH 7, activity is strongly suppressed at pH 6.0 (pH 6.0/pH 8.0~0.35), low affinity to UDP-GalNAc (high/low~2) and 2'-fucosyllactose [3][4][5], and Aint-enzyme: low activity in plasma. pH optima at pH 7, activity lower at pH 6.0 (pH 6.0/pH 8.0~0.9), high affinity to UDP-GalNAc (high/low~ 1.15) but very low affinity to 2'-fucosyllactose [6]. Based on these kinetic criteria, subjects a-2, a-3, and b-1, serologically classified as AjB or AintB, are definitely A2B, while subjects c and d with similar serological characters were found to be AintB on the enzyme ba sis.…”

Section: Blood Types Determined By the Enzyme Testmentioning

confidence: 99%

“…The observed high inci dence of A2B in comparison to A2 in some Black populations can be explained by the existence of the superactive atypical B-enzyme and the ambiguity of identification of A2B and AintB by the agglutination test. The frequency of Aim is reported to be about 1 % [13] and 2.5% [6] of A in Cau casians, while it is about 10% [9] and 32% [6] of A in Blacks.…”

Section: Blood Types Determined By the Enzyme Testmentioning

confidence: 99%

“…In these cases, therefore, the forma tion of A substances was suppressed by the competition with the superactive B-en zyme for the common H-sites, resulting in expression of A2 character. Since the fre quency of Aint gene is very high in Blacks [6,9], the observed imbalance, i.e. A |B/ A2B < A |/A 2, in Blacks could be partly attributed to misclassification of AintB as A2B by the agglutination test.…”

mentioning

confidence: 99%

“…The distinction of A|B, A2B, and AintB by the agglutination test is more ambiguous than that of A]( A2, and Aint, since the formation of A substances would be disturbed by the coexisting B-enzyme [6], The agglutinability of red cells with the H-lectin cannot be used as a criteria for distinction of the subtypes in AB red cells.…”

mentioning

confidence: 99%

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Uncertainty in Identification of Blood Group A Subtypes by Agglutination Test

1985

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Identification of the blood group A subtypes, i.e. A₁, A₂, and A₁-A₂ intermediate (Aint), by agglutination test, particularly in AB red cells, is ambiguous. The expressions of A subtypes in red blood cells are the consequences of diverse formations of the A substances by the action of three types of blood group N-acetyl-galactosaminyl-transferases controlled by A₁, A₂, and Aint genes. Therefore, the A subtypes are more directly identified by examining the kinetic characters of A-enzymes existing in plasma. Several Black AB subjects classified as non-A₁ by the agglutination test were identified as A₁B and AintB on the enzyme basis. A subject serologically classified as A₁ had A₂-enzyme in her plasma, i.e. she is genetically A₂O or A₂A₂. The present and previous studies indicate that red cell A₂ status is occasionally expressed as a result of the combination of Aint and B, and of A₁ and superactive B. The imbalance between A₁/A₂ and A₁B/ A₂B observed in some Black populations could be attributed to high frequencies of the Aint and B. sup. genes in Blacks.