ORIGINAL PAPER: Dombrock gene analysis in Brazilian people reveals novel alleles

The Doa and Dob polymorphisms are associated with three single nucleotide polymorphisms (SNPs) in exon 2 of the DO gene: 378C/T, 624T/C and 793A/G for the DOA and DOB alleles, respectively. The SNPs 350C/T (JO allele) and 323G/T (HY allele) are associated with the Jo(a-) and Hy-negative phenotypes. Recently, two new DO alleles [DOB-SH (378C, 624C, 793G) and DOA-HA (378T, 624T, 793A)] were identified using microarray technology. Although the molecular background of Dombrock alleles is well defined, no studies have been conducted in the Brazilian population. We employed polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)-based assays and a microarray assay to determine the frequency of the DO alleles (DOA, DOB , HY1, HY2 and JO ) in Brazilians. We tested DNA of 288 Brazilians from three different ethnic groups by PCR-RFLP to determine the 793A/G (DOA/DOB ), 323G/T (HY ), 350C/T (JO ) and 898C/G (HY1 /HY2 ) SNPs. We also tested DNA from 162 blood donors by using the HEA Beadchip(TM) assay to determine the 378C/T, 624T/C, 793A/G (DOA /DOB ), 350C/T (JO allele) and 323G/T (HY ) SNPs. Two novel allele combinations were found in our samples: the DOB allele (793G and 323G) associated with 898G (DOB-WL ); and an allele carrying the nucleotides 378C, 624C, 793A and 323G (DOA-SH ). We also found the DOB-SH and DOA-HA .alleles recently reported. Our data demonstrate high heterogeneity of DO alleles in the Brazilian population. Our study also highlights the importance of testing a cohort of different populations to determine DO haplotypes and of establishing reliable genotyping tests for predicting Doa/Dob status. [PUBLICATION ABSTRACT]