Prevalence of A2 and A2B Blood Group Subgroups Among Blood Donors in Al-Qurayyat, Saudi Arabia: A Cross-Sectional...

The A2 and A2B subgroups are of clinical importance because some A2 and, more often, A2B individuals may produce anti-A1 antibodies that can cause hemolytic transfusion reactions, and their frequency varies across populations. As no data were available for Al-Qurayyat, northern Saudi Arabia, this study determined the prevalence of the A2 and A2B subgroups among local blood donors and their distribution by RhD status.

A cohort of 247 samples previously typed as blood group A (n=202) or AB (n=45) at a local blood bank (5 September to 14 November 2024) was subtyped with anti-A1 lectin (Dolichos biflorus) by the standard tube technique, and proportions were expressed with 95% Wilson confidence intervals.

Within group A, 153 samples (75.74%) were A1 and 49 (24.26%) were A2, whereas within group AB, 26 (57.78%) were A1B and 19 (42.22%) were A2B; relative to all A-antigen-positive donors, the A2 and A2B frequencies were 19.84% and 7.69%, and 226 donors (91.5%) were RhD positive. The proportion of A2-type phenotypes was significantly higher in group AB than in group A (χ²=5.09; p=0.024).

These serologically defined frequencies exceed those reported in the included regional comparator studies and may support routine anti-A1 lectin subgrouping, although molecular confirmation is warranted.