A case study of severe hemolytic disease with the newborn caused by DIVb type of RhD variant

Abstract

Objective To study a case of severe hemolytic disease with the newborn induced by DⅣb type of RhD variant and to investigate its molecular mechanism .Methods Indirect Coombs test was performed to identify RhD blood type and detect antibodies against red blood cells （RBCs）.RHD genes were analyzed by polymerase chain reaction-sequence specific primers （PCR-SSP） analysis.All of the 10 exons of RHD gene were sequenced .The Rhesus boxes were further analyzed to identify the homozygosis of RHD genes.Results The mother of the newborn was RhD positive carrying anti-D antibody.PCR-SSP analysis indicated that the RHD exons 7-9 were missing, although the sequences of other RHD exons were consistent with standard sequences .RHD zygosity test showed that the mother was RHD＋/RHD-.The newborn was RhD positive with anti-D antibody in serum .The result of the direct antiglobulin test was also positive .The sequence of the RHD exons 1-10 of the newborn were identical with standard sequences .The genotype of the newborn was identified as RHD＋/RHD＋homozygote .Conclusion The mother bears a DⅣb genotype lac-king RHD exons 7-9 which is significantly different from the newborn .The anti-D antibodies in the mother might induce the severe hemolytic disease in the newborn . Key words: RHD gene; D variant; DⅣb type; Hemolytic disease of the newborn