HLA-A and hydrops fetalis: From the 4-locus (HLA-A-B-DRB1-DQB1) haplotype frequencies (HF), the most frequent haplotype in this cohort was: HLA-A*26:01 ~ B*08:01 ~ DQB1*02:01 ~ DRB1*03:01 (HF: 1.85%).