Objectives: The aim of this study was to determine the agreement between AB blood phenotyping and genotyping and determine whether non-AB blood type incompatibilities exist in UK cats.
Methods: Blood samples underwent phenotyping (A, B or AB) using microplate agglutination, and genotyping (AA, Ab or bb) using pyrosequencing of a fragment of the cytidine monophospho-N-acetylneuraminic acid hydroxylase gene. Non-AB blood type incompatibilities were investigated by cross-matching against reference blood of the same phenotype.
Results: Of 112 cats tested, 86 (77%) were blood phenotype A, 19 (17%) type B and 7 (6%) type AB. Genotype and initial phenotype agreed in 96% (107 of 112) of cats, but 5 were discordant; these were all B phenotype with either AA (n=2) or Ab (n=3) genotype. Two of the five cats had repeat blood samples tested: one was reclassified as phenotype A; the other remained phenotype B. Two cats had incompatibilities on minor cross-match, but these were attributed to phenotyping errors.
Clinical significance: Unknown mutation(s) associated with phenotype B, resulting in false AA or Ab genotyping, were evident in a small number of cases in this study. No conclusive evidence for non-AB blood type incompatibilities was found.