Frequencies of human neutrophil antigen-4 and human neutrophil antigen-5 among Thai blood donors

CONTEXT: Antibodies against human neutrophil antigens (HNAs) are implicated in immune-mediated neutropenia, transfusion-related acute lung injury and febrile transfusion reactions. AIMS: This study aimed to determine HNA gene frequencies of the HNA-4 and HNA-5 systems among Thai populations and compare these frequencies with those previously reported for other populations. MATERIALS AND METHODS: 800 DNA samples obtained from 500 unrelated healthy blood donors from Bangkok and 300 samples from Chiang Mai, Thailand were included. Samples were typed for each HNA allele including HNA-4a, HNA-4b, HNA-5a, and HNA-5b using an in-house polymerase chain reaction with sequence-specific primer technique. RESULTS: The frequencies of HNA-4a and HNA-4b alleles in central Thais were 0.975 and 0.025, respectively and for Northern Thais, their frequencies were 0.965 and 0.035, respectively. For HNA-5a and HNA-5b alleles, their frequencies were 0.771 and 0.229; 0.748, and 0.252 in central and Northern Thais, respectively. The frequencies of HNA-4 and HNA-5 systems in central Thais are closely related to those in Northern Thais (P > 0.05). However, their frequencies were different from other populations (P < 0.001), except HNA-5a and HNA-5b gene frequencies in Thais were similar to Caucasians (P > 0.05). CONCLUSION: This study could contribute to predict the risk of alloimmunization to HNA-4 and HNA-5 systems, especially in feto-maternal incompatibility in Thais.