OBJECTIVEPreviously the weak D and D category allele were investigated in Caucasian and Japanese families. The current study is aimed at an RHD positive, D antigen negative allele in a Chinese family.

METHODSA pair of primers specific for RHD 270A allele were designed, and a sequence specific primer-PCR (SSP-PCR) method was then established to detect RHD 270A allele in 6 members of a family. Furthermore, RFLP method was used to determine the RHD zygosity in all family members.

RESULTSThe RHD 270A allele was detected in the proband, her father and uncle but not grandmother. Therefore this allele may be from grandfather and is inherited through 3 generations. The RHD zygosity test showed that the father and uncle possess one normal RHD gene as RHD 270A carriers, the mother is RHD(+)/RHD(-)heterozygote and the individual is RHD 270A/RHD(-)which causes an RHD positive, D antigen negative trait.

CONCLUSIONThe RHD 270A allele is an ancestral allele, but not a spontaneous.