Nuchnoi P.Thongbut J.Bénech C.Kupatawintu P.Chaiwanichsiri D.Férec C.Fichou Y.Mahidol University2023-05-272023-05-272023-05-01Blood transfusion = Trasfusione del sangue Vol.21 No.3 (2023) , 209-217https://repository.li.mahidol.ac.th/handle/20.500.14594/82859BACKGROUND: Discriminating individuals with "Asian type DEL" from those who are "true D-negative" (D-) among serologically D- donors/patients in Asia would be very valuable, as clinical outcomes are different in these groups. Here we investigated the molecular basis of D-negativity in Thai blood donors, designing a specific strategy for this purpose. MATERIALS AND METHODS: After routine testing, a total of 1,270 serologically D- blood donors originating from Central, Northeastern and South Thailand underwent analysis of the RHD gene by (i) quantitative multiplex polymerase chain reaction of short fluorescent fragments (QMPSF); (ii) direct sequencing of exon 9 to identify the c.1227G>A variant defining the Asian type DEL allele; and (iii) direct sequencing of the other exons. RESULTS: The most common observation was whole deletion of the gene (i.e. RHD*01N.01; allele frequency: 86.81%), followed by the Asian type DEL allele (RHD*01EL.01; 7.60%) and a D-negative hybrid allele (RHD*01N.03; 3.46%). Four novel alleles, including one with a 13.1 kilobase-deletion, were identified and characterized. All but one RHD*01EL.01 allele carriers (183/184) were C-positive (C+), suggesting that this latter subset may be screened specifically when investigating the c.1227G>A variant, which can be identified with 100% accuracy by a specific Tm-shift genotyping assay. DISCUSSION: On the basis of our extensive molecular findings, we have designed a dedicated diagnostic strategy based on Rh C antigen typing followed by a genotyping test. Implementation of this method in all or selected groups of serologically D- donors/patients will contribute to improve the management of transfusion and pregnancy in Thailand.MedicineArticleSCOPUS10.2450/2022.0160-222-s2.0-851595526572385207036346882