Background: SERF(+) is a high prevalence antigen in the Cromer blood group system that is encoded by a CROM*01.12 allele. The SERF(-) on red cells is caused by a single nucleotide variation, c.647C＞T, in exon 5 of the Decay-accelerating factor, DAF gene. Alloanti-SERF was found in a pregnant Thai woman, and a SERF(-) individual was found among Thai blood donors. Since anti-SERF is commercially unavailable, this study aimed to develop appropriate genotyping methods for CROM*01.12 and CROM*01.-12 alleles and predict the SERF(-) phenotype in Thai blood donors. Methods: DNA samples obtained from 1,580 central, 300 northern, and 427 southern Thai blood donors were genotyped for CROM*01.12 and CROM*01.-12 allele detection using in-house PCR with sequence-specific primer (PCR-SSP) confirmed by DNA sequencing. Results: Validity of the PCR-SSP genotyping results agreed with DNA sequencing; CROM*01.12/ CROM*01.12 was the most common (98.42%, 98.00%, and 98.59%), followed by CROM*01.12/CROM*01.-12 (1.58%, 2.00%, and 1.41%) among central, northern, and southern Thais, respectively. CROM*01.-12/CROM*01.-12 was not detected in all three populations. The alleles found in central Thais did not significantly differ from those found in northern and southern Thais. Conclusion This study is the first to distinguish the predicted SERF phenotypes from genotyping results obtained using in-house PCR-SSP, confirming that the CROM*01.-12 allele frequency ranged from 0.007 to 0.010 in three Thai populations. This helps identify the SERF(-) phenotype among donors and patients, ultimately preventing adverse transfusion reactions.

Background: The Kidd (JK) blood group system is of clinical importance in transfusion medicine. JK*A and JK*B allele detections are useful in genetic anthropological studies. This study aimed to determine the frequencies of JK*A and JK*B alleles among Muslim blood donors from Southern Thailand and to compare how they differ from those of other populations that have been recently studied. Methods: A cross-sectional study was used. Totally, 427 samples of dissimilar Thai- Muslim healthy blood donors living in three southern border provinces were selected via simple random sampling (aged 17–65 years old) and donors found to be positive for infectious markers were excluded. All samples were analysed for JK*A and JK*B alleles using PCR-SSP. The Pearson’s chi-squared and Fisher exact tests were used to compare the JK frequencies among southern Thai- Muslim with those among other populations previously reported. Results: A total of 427 donors—315 males and 112 females, with a median age of 29 years (interquartile range: 18 years)—were analysed. A JK*A/JK*B genotype was the most common, and the JK*A and JK*B allele frequencies among the southern Thai-Muslims were 55.2% and 44.8%, respectively. Their frequencies significantly differed from those of the central Thai, Korean, Japanese, Brazilian–Japanese, Chinese, Filipino, Africans and American Natives populations (P < 0.05). Predicted JK phenotypes were compared with different groups of Malaysians. The Jk(a+b+) phenotype frequency among southern Thai-Muslims was significantly higher than that of Malaysian Malays and Indians (P < 0.05). Conclusions: The JK*A and JK*B allele frequencies in a southern Thai-Muslim population were determined, which can be applied not only to solve problems in transfusion medicine but also to provide tools for genetic anthropology and population studies.