Molecular basis and zygosity determination of D variants including identification of four novel alleles in Chinese individuals.

BACKGROUND: The frequency and molecular basis of the D variants have been reported in the Caucasian and African populations, but relatively little information was known in the Chinese population. Here, a study was investigated in Chinese persons with weak or discrepant D serologic typing. STUDY DESIGN AND METHODS: D variant was typed with a serologic method. The full coding regions of RHD of these variants were amplified with polymerase chain reaction and then directly sequenced. RHD zygosity test was performed using the hybrid Rhesus box technique and a multiplex ligation-dependent probe amplification (MLPA) assay was also used to analyze the variant alleles and RHD gene copy number. RESULTS: Twelve distinct RHD mutation alleles were found in 32 D variant individuals, with eight weak D and four partial D alleles. Weak D Type 15 and DVI Type 3 were the major weak D and partial D alleles in Zhejiang Han persons. Three novel weak D alleles (RHD weak D 95A, 779G, and 670G) and one new partial D allele (RHD130-132 del TCT) were identified. The results of RHD zygosity in three individuals disagreed between the RHD zygosity test and the MLPA assay. The most known variant alleles can be detected, but four novel alleles were missed using the RH-MLPA assay. CONCLUSION: The molecular basis and zygosity of D variants in Zhejiang Han persons were analyzed, and four novel RHD alleles were identified. These data extend the information of D variants and may help to improve the transfusion strategy of the D variants.