| We use monoclonal IgM anti D antibody in screening RhD antigensfor 22361 pregnant women, and found that 128 cases are Rh negative blood type, accounting for 5.72 per thousand. Further using of indirect antiglobulin test,we found 3 cases were positive.Anti D antibody is a precursor of Rh negative pregnant women in RH neonatal hemolytic disease.By screening and monitoring the irregular antibody for 128 cases of Rh negative pregnant women, we found that 2 cases is positive, and the antibody is anti-D. Among them 1 case,G2P1,first irregular antibody screening test is negative. After the amnion acupuncture in 22 weeks, she injected the D immune globulin. But a month later,irregular antibody is found. Anti D produced, and anti D titer increased with the pregnancy, although after the injection of immune globulin therapy, and severe infant jaundice, RHD hemolysis disease happened. Another 1 case, G1P0, the first irregular antibody screening was negative, But at the end of the pregnancy we found the irregular antibody, and convinced it is anti D.But no neonatal hemolytic disease happened because anti D titer is very low.By indirect antiglobulin test,125 cases are negative, including D antigen negative individuals of RHD gene D antigen entirely missing and DEL individuals of D antigen expression very weak. By Genotyping with PCR-SSP and sequencing,104 cases are entirely missing RHD gene D antigen,21 cases are DEL. By indirect antiglobulin test,3 cases are positive including weak D and part D. By genotyping with PCR-SSP and sequencing,2 cases are weak D(D15 type); 1 case is part D(D Ⅵ type Ⅲ). Among 128 cases of RhD negative blood grouping, 81.25% individuals are D antigen negative,16.4% individuals are DEL,1.56%individuals are D15,0.78% individuals are D VI type Ⅲ. According to reports in the literature, in China,D antigen negative is majority among Rh D negative blood group in the han population; DEL is given priority to D antigen variant; D15 is given priority to weak D; D Ⅵ type Ⅲ is given priority to part D. Our results are consistent with literature reports.2 individuals produced the same immune antibodies. Their genotypes were RHD gene D antigen entirely missing, including 1 case happened hemolytic disease of newborn. In serological we distinguish D antigen negative and DEL by absorption-tossing test. DEL is due to the RhD intracellular mutations, and affect the RhD integration into the red cell membrane,that resulting in a loss on the red cell membrane copy number.But extracellular area has no change,and has complete antigen epitope,which has a qualitative difference with D antigen negative. There’s high false negative rate in identificating DEL by the absorption-tossing test, so we use genotyping method to distinguish D antigen negative and DEL.In Chinese han population, D15 is given priority to weak D; D Ⅵ type Ⅲ is given priority to part D. They both have the same immune risk. In addition, They have some other subtypes. Different subtypes have different clinical effects.So we should combine serological phenotype and genotype to make a risk assessment for Rh negative blood type individuals.At present, in our country, we use serological methods to identify maternal Rh blood type and to classify D antigen negative,part D, weak D and DEL,in order to prevent occuring Rh hemolytic disease of newborn.But serological method has certain limitations. On the one hand, it is difficult to distinguish variations within weak D, part D, and DEL, and different subtypes have different risks; On the other hand, DEL false negative rate is higher as we distinguish DEL and D antigen negative. Therefore/we should use genotyping methods to classify D antigen negative,part D, weak D and DEL.We should combine serological phenotype and genotype and clinical effects to reduce the risk of Rh neonatal hemolytic disease. |
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