OBJECTIVETo analyze the sequences of Rhesus boxes of RhD gene, and explore the genetic mechanism of RhD negative phenotype in Chinese Han population. Meanwhile the PCR product of Rhesus boxes is analyzed for determining RHD gene homozygosity.

METHODSDNA of 74 RhD negative samples were firstly analyzed with multiplex PCR-sequence specific primer(SSP). The further analysis was given to Rhesus boxes specific sequencing and RHD gene homozygosity determined by PCR-restriction fragment length polymorphism(RFLP) analysis to Rhesus boxes.

RESULTSIn DNA samples of 74 RhD negative individuals, 46 samples(62%) showed the absence and homozygous negative of RHD gene; 22 samples(30%) all showed the existence of RHD specific exons, of which 19 were RHD gene heterozygous and 3 were homozygous; regardless of PCR-RFLP analysis showing no RHD specific exons, but further analysis of RHD specific PCR revealed one RHD gene, at least RHD gene exon 1 and 10 existing in 5 DNA samples(7%); 1 sample(1%) was lacking RHD exon 6 although the multiplex PCR showed the RHD gene to be positive. Analyzing the hybrid Rhesus box of 27 RhD negative samples revealed the Han Chinese population to have the same DNA sequence of hybrid Rhesus box as Caucasians.

CONCLUSIONThe RHD gene deletion is the main molecular mechanism of causing RhD negative formed in Han Chinese population, who have had the RHD gene deletion taken place within the defined breakpoint region as Caucasians.