Genetic background of anti‐Xg^a producers in Japanese blood donors

Abstract

Background and Objectives: The Xg blood group is composed of two antigens, Xg a (XG1) and CD99 (XG2 and MIC2). The XG and CD99 are homologous genes located on pseudoautosomal region 1 of the X and Y chromosomes. The expressions of Xg a and CD99 are co-regulated by a single nucleotide polymorphism (rs311103) in the GATA-1 binding region. Another mechanism of the Xg(aÀ) phenotype is the genomic deletion of approximately 114 kb, including the XG gene. Anti-Xg a seems to be naturally occurring by detection in males who have never been transfused. Materials and Methods:In this study, we identified 23 anti-Xg a producers among 580,115 donors (0.004%). Additional 12 anti-Xg a producers were also identified from a separate cohort.Results: All 35 anti-Xg a producers were male. Genomic DNA was obtained from 34 of 35 producers, and all 34 producers were confirmed to carry the XG-genedeficient allele (XGdel). The breakpoints of all 34 producers were identical. The XGdel was also identified in 12 non-producers of anti-Xg a among 860 donors who have no antibodies against RBCs, and the breakpoints were also identical with the anti-Xg a producers. Conclusion:Our results will serve as the basis for a more complete understanding of Xg blood group polymorphisms.

Prevalence and molecular basis of null blood group phenotypes in the Korean population: Analysis using a public database

“…Another limitation is that some null phenotypes such as Xg(aÀ) are primarily caused by structural variants such as large deletions difficult to detect with WGS data. 22 In addition, the assumption of Hardy-Weinberg equilibrium may not be valid for very rare alleles. 23 Finally, the KRGDB lacks the zygosity information of sequence variants.…”

“…A major limitation of this study is that probable null alleles found in this study were neither observed in individuals with null phenotypes nor confirmed to induce null phenotypes in in vitro experiments. Another limitation is that some null phenotypes such as Xg(a−) are primarily caused by structural variants such as large deletions difficult to detect with WGS data 22 . In addition, the assumption of Hardy–Weinberg equilibrium may not be valid for very rare alleles 23 .…”