THE RhDel ALLELE IN THE JAPANESE POPULATION

The RHD gene of D-negative Japanese individuals was analyzed to determine the causes of the D-negative phenotype. cDNAs prepared from reticulocytes were used for the sequencing of full length RH transcripts. Although the complete RHCE sequence was obtained from the cDNA clones of D-negative and RHD gene-positive (D-RHD +) individuals, the complete sequence of RHD was not. The longest sequence derived from RHD had exon 9 deleted. A synonymous one-point mutation, G1227A, at the 3′-end of exon 9 was found in the genomic DNA. The allele was shared by more than 90% (28/31) of D-RHD +individuals, most of whom had the Del phenotype. To distinguish the Del, allele from D-positive alleles, a multiplex PCR-SSP (sequence specific primer) method was designed.