Identification of Lutheran Blood Groups and Genetic Variants within KLF1 among Thai Blood Donors.

Background: Lu^a and Lu^b are inherited as codominant allelic characters resulting from a single nucleotide variant (SNV) of the basal cell adhesion molecule (BCAM) gene. Red cells of the dominantly inherited suppressor of the Lutheran antigens In(Lu) phenotypically appear as Lu(a-b-) by the haemagglutination test. In(Lu) resulted from heterozygosity for mutations within the erythroid-specific Krüppel-like factor 1 (KLF1) gene. This study aimed to determine the frequency of the Lu(a) and Lu(b) phenotypes and genotypes and genetic variants of the distinct In(Lu) among Thai blood donors.

Material and methods: Samples from 334 Thai donors were phenotyped with anti-Lu^a and anti-Lu^b. These DNA samples and an additional 1,370 donor DNA samples with unknown Lu(a)/Lu(b) phenotypes were genotyped using an in-house PCR-SSP. In the case of the three Lu(a-b-) donors, the BCAM and KLF1 genes were analysed by PCR and sequencing.

Results: A total of 331 of the 334 donors were Lu(a-b+), while the other observed phenotype, appearing as Lu(a-b-), was found among three donors. Of those three Lu(a-b-) donors with the LU*02/02 genotype, we identified KLF1 variant alleles, consisting of two variants: c.[304T>C, 1001C>G] and c.[304T>C, 519_525dupCGGCGCC], leading to the In(Lu) phenotype, and one homozygous variant (c.304T>C) mutation. Also, only one Thai donor was genotyped as LU*01/02, confirmed by serology test and DNA sequencing.

Conclusion: In this study, we identified KLF1 variants to be included in Lutheran typing analysis in Thai populations. Therefore, the application of genotyping and phenotyping methods has simultaneously been in use to screen and confirm the rare Lu(a+) and In(Lu) phenotypes.