The increasing need for ABO blood group genotyping and quality assurance implications for laboratory implementation.

ABO blood group antigens are critical determinants of immunologic self and non-self and are ubiquitously expressed on all cellular tissues. Antibodies against non-self ABO antigens are naturally present and can mediate pathologic reactions against incompatible transfused blood cells and transplanted tissues. Laboratory testing for ABO antigens and isoagglutinins is essential for safe and effective transfusion and transplantation. Testing for ABO antigens has traditionally depended on serologic testing. However, there is increasing need for evaluation of genetic analysis of ABO antigens, to enable evaluation of ABO blood group in cases where serologic testing may be ambiguous or impossible to accurately perform. The clinical need for ABO genotyping is being addressed by the development of multiple molecular diagnostic approaches. Recent data have clearly demonstrated the potential utility of ABO genotyping in solid organ transplantation, yet widespread implementation has been slow. We propose that this lag is related to practical considerations in laboratory testing, including limited regulatory guidance on the performance and reporting of these assays and the absence of widely available external proficiency testing programs for quality assurance. Here we describe approaches to ABO genotyping, current initiatives in developing ABO genotyping proficiency testing programs, and laboratory quality assurance considerations for ABO genotyping.