Molecular characterization of CD36 deficiency in blood donors of Middle Eastern and African origin reveals transcript-level defects beyond genomic variants.
BACKGROUND: The increasing diversity of blood donor populations has created new challenges for transfusion services worldwide. The identification of donors lacking relevant high-prevalence antigens is becoming increasingly important to ensure compatible blood products for alloimmunized patients and to support the development of rare donor registries. CD36 (ISBT 045) is a glycoprotein expressed on platelets, monocytes, and erythroid precursor cells. CD36 deficiency has been reported across multiple populations and is of relevance due to its association with anti-CD36 isoantibodies, which may cause platelet transfusion refractoriness and fetal/neonatal alloimmune thrombocytopenia. STUDY DESIGN AND METHODS: We analyzed CD36 expression in 1250 blood donors of diverse ancestry using flow cytometry. CD36-negative samples underwent molecular characterization using Sanger sequencing and next-generation sequencing of genomic DNA, complemented by cDNA analysis and cloning to investigate transcript-level alterations. RESULTS: We identified CD36 deficiency in 27 donors (2.16%). Genomic sequencing revealed 18 distinct coding variants, including three novel variants, most in the heterozygous state. In one CD36-negative donor, cDNA analysis demonstrated a 52-bp deletion in exon four and complete skipping of exon 9, despite the absence of splice-site variants in genomic DNA. Cloning confirmed coexistence of aberrant and wild-type transcripts in this individual. CONCLUSION: Our findings demonstrate that CD36 deficiency can arise from transcript-level defects in the absence of detectable coding or splice-site variants. These results indicate that genomic sequencing alone may be insufficient to fully resolve CD36-negative phenotypes and highlight the importance of integrating transcriptomic approaches to improve molecular diagnostics and transfusion support in increasingly diverse donor populations.