Asian-type DEL among D-negative patients and donors in Malaysia can ease the demand for D-negative red cells and RhIG

In East and Southeast Asia, D-negative blood units and donors are rare (<0.5%). A recent prospective clinical trial suggested that patients with the Asian-type DEL (<i>RHD*DEL1</i>) can be safely managed as D-positive. However, despite a clinically relevant prevalence of Asian-type DEL (typically 17%) in East Asia, data on its prevalence in the Malay population were lacking. We reviewed Rh phenotyping records of blood donors in Terengganu, Malaysia, collected over 4 years, and conducted molecular analysis of the <i>RHD</i> gene on serologic D-negative blood donors and patient samples collected in 2024. Among 33 829 blood donors, 179 (0.53%) were serologic D-negative, with the highest prevalence (5%) in Indian donors. The prevalence of Asian-type DEL was found to be 25% among Malay D-negative blood donors and 21% among Malay patients, higher than in most East Asian populations. The findings suggest that implementing red cell genotyping can improve the precise allocation of red cell resources, conserve the supply of rare D-negative blood, and eliminate unnecessary RhIG injections.