Extended Blood Group Genotyping Among Thai Patients with Repeated Transfusions.

Background: Transfusion of antigen-negative red blood cells (RBCs) is required for patients with chronic transfusions. Due to serological test limitations, genotyping is implemented to find appropriate and compatible blood units. This study aimed to determine extended blood group genotypes to identify antibody specificity and to establish appropriate typing for Thai patients with repeated transfusions.

Methods: Blood samples obtained from 200 unrelated Thai patients with repeated transfusions, at the Thammasat University Hospital, Pathum Thani, Thailand, were included. The patients had recently received at least three units of donor RBCs within 3 to 12 weeks at the time of blood collection. Extended blood group genotyping using the PCR-sequence-specific primer technique determined KEL*03, KEL*04, DI*A, DI*B, DO*A, DO*B, CO*A, CO*B, CROM*01.12, and CROM*01.-12 alleles.

Results: Among 200 patients, no significant difference was found between male and female ratios (p > 0.05). Concerning the antibody production divided by patients' diagnoses, we found that only 2 patients with chronic kidney disease, CKD, (6.3%) had significantly lower antibody detection than patients with thalassemia, hematological and other malignancies, and other disorders (p < 0.05). Based on extended blood group allele patterns among 200 patients and 500 donors, the two common allele patterns were first: KEL*04, DI*B, DO*B, CO*A, and CROM*01.12 (75.0 vs. 71.0%), and second: KEL*04, DI*B, DO*A, DO*B, CO*A, and CROM*01.12 (18.0 vs. 21.6%), consistent with the donor population. As a result, this patient group showed a high chance of identifying matched donors and a low risk of alloimmunization. The prevalence of the DI*A/DI*B heterozygote was observed at 4.6% among 500 donors, corresponding to the high prevalence of anti-Dia in the patient group. Therefore, extended blood group genotypes, particularly the common significant blood group antigens in populations, are helpful among patients requiring repeated transfusions.

Conclusions: Extended blood group genotyping among patients with repeated transfusions should be performed to select antigen-negative RBC transfusions. However, the prevalence of antibody production and the additional blood group antigens corresponding to high-prevalent antibody identification among Thai patients should be a concern in proper blood group selection.