1. Genetic background of anti-CD99 producers in Japan and analysis of hemolytic transfusion reactions due to anti-CD99.
- Author
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Watanabe-Okochi N, Tsuneyama H, Kumamoto M, Tanaka S, Nakazono T, Ichinomiya K, Suzuki Y, Ogasawara K, Uchikawa M, Naganuma S, Hayashi S, Igarashi H, Tsuno NH, and Muroi K
- Abstract
Background: The XG blood group system comprises two antigens, Xg
a and CD99. CD99 is known to be carried on both the X and Y chromosomes in pseudoautosomal region 1. We identified five unrelated Japanese individuals with anti-CD99 and investigated their genomic background as well as the clinical significance of anti-CD99., Study Design and Methods: Analysis of CD99 expression on RBCs and a modified monocyte monolayer assay was performed using flow cytometry. Genomic DNA was obtained from the five anti-CD99 producers to identify the deleted region responsible for the lack of CD99, and we conducted a long polymerase chain reaction using primer pairs specific for CD99 and GYG2., Results: CD99 expression from the Y chromosome was higher than that from the X chromosome. The five anti-CD99 plasma samples gave varied agglutination strengths with the red blood cells (RBCs) expressing high and low CD99 levels, in the antiglobulin test. The phagocytosis rate of anti-CD99-sensitized RBCs was 76.6% in one case indicating a risk of hemolytic transfusion reactions (HTR), and it correlated with the level of CD99 expression. The deleted region spanned 115 kb, from CD99 exon 3 to GYG2 exon 1. All five anti-CD99 producers were homozygous for the large deletion allele., Discussion: All five anti-CD99 producers were females with a history of pregnancy in Kyushu, Japan, and this deletion allele may thus be endemic. Our results indicated the possibility of HTR due to anti-CD99, and the risk is low when transfusing RBC products from Xg(a-) females with a low expression of CD99., (© 2025 AABB.)- Published
- 2025
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