Molecular basis of Bombay phenotype in Mashhad, Iran: identification of a novel FUT1 deletion.

BACKGROUND AND OBJECTIVES: Bombay phenotype is characterized by the lack of H substance both on red blood cell (RBC) surface and in body secretions. Mutations of fucosyltransferase 1 (FUT1) and fucosyltransferase 2 (FUT2) genes are resulted in this rare phenotype.

MATERIALS AND METHODS: Five unrelated patients were tested by hemagglutination and adsorption/elution techniques for the presence of ABH antigens. The saliva specimens were analysed by hemagglutination inhibition method. The exons 6 and 7 of ABO gene were sequenced to determine ABO genotype. The coding fragments of FUT1 and FUT2 were amplified and sequenced by specific primers.

RESULTS: Serologic investigation confirmed Bombay phenotype in all individuals. FUT1 molecular analysis revealed a novel large deletion. Also two novel homozygous mutations were detected; one was a missense mutation (392T>C, L131P) and the other a three nucleotide deletion (668_670delACT, Y224del). FUT2 sequencing showed one reported null allele (428G>A, W143X) and one homozygous deletion of FUT2.

CONCLUSION: Although FUT2 deletion has been reported, this is the first report of FUT1 deletion. Finding two FUT1 novel alleles in Iranian people is indicative of mutation diversity in this gene.