[Molecular genetic analysis of a family with a rare ABw31 subgroup]

To analyze a family where some members were suspected as rare ABw31 subtype.

Serological assay was performed to identify the ABO blood group of the proband and other family members. Genotypes for exons 6 and 7 of the ABO gene were determined with sequence-specific primer polymerase chain reaction (SSP-PCR) and direct sequencing.

Both A and B antigens were detected on the red blood cells from the proband. There was also anti-A antibody in the serum. The serological phenotype of the sample was identified as ABw. DNA sequencing confirmed heterozygous status of 297AG, 467CT, 526CG, 657CT, 664GA, 703AG, 796AC, 803GC, and 930GA for exons 6 and 7. Clone of two alleles (A102 and Bw31) were obtained. Compared with the B101 allele, sequence of Bw31 allele showed one nucleotide change (G to A) at position 664, which resulted in replacement of Val with Met at position 222. The proband's father, brother and son all carried the Bw31 allele.

The 664G>A mutation probably underlies the Bw phenotype and can be transmitted stably.