Background and objectives: The human Secretor alpha(1, 2)fucosyltransferase gene determines the ABH secretor status and influences the Lewis phenotype of an individual. Studies were carried out on the Lewis (a+b-) nonsecretors of different groups indigenous to Taiwan to demonstrate their se genotypes.
Methods: The Lewis phenotype of the blood samples was determined by a microplate method. The se genotypes of the individuals with the Lewis (a+b-) phenotype were analyzed by a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method designed for the se alleles reported previously. PCR and cloning techniques were used to determine the coding sequence of the novel se gene.
Results: A new se allele, se685, with a three-nucleotide deletion of GTGGT to GT in the coding region of nucleotides 685 through 689 was identified in a Le (a+b-) nonsecretor from the Ami tribe indigenous to Taiwan. The deletion predicts the loss of the amino acid Val230 in the corresponding secretor enzyme's C-terminal segment. The distribution of the se685 allele in the Ami tribe was further verified by PCR-RFLP analysis.
Conclusion: The Se gene exhibits heterogeneity with some Se alleles being common but others displaying a unique distribution in different ethnic populations. The newly identified se685 allele seems to exist only in the Ami tribe indigenous to Taiwan.