Interindividual variation in HLA-B8, B12, and B35 expression on PLTs is only partially explained by homozygous or heterozygous haplotypes. HLA-B8– (A), -B12– (B), and -B35–positive (C) donors were divided in 2 groups based on zygosity. Relative expression is presented as median ± interquartile range, and each donor is represented by one symbol. Background staining is depicted with the dotted line. Expression between heterozygous and homozygous donors was compared with an unpaired Student t test, and a F-test was used to investigate differences in variation between groups. Statistical significance is depicted as **P < .01, ***P < .001, ****P < .0001; ns, not significant.