The Clinical And Laboratory Study Of Haemolytic Disease Of Fetus And Newborn Of RhD-incompatibility Between Mother And Child

Objective RhD-- deletion is a rare variant in Rh-blood groupsystem which is characterized by the complete absence of RhC/c,E/eantigen and(or) overexpression of D antigen on the red blood cells. Atpresent, the molecular mechanism of RhD-- deletion is unclear, but thereare two possibilities contributing to it: first, the RHCE gene is intact butno expression at all; second, the RHCE gene is partially deleted. The firstis occurred in the mRNA transcription regulation level and the secondmay include exons deletion or gene recombination. RhD-- deletionindividuals are easily get immunized and can produce high titeranti-RhC/c,E/e antibody (i.e.anti-Hro antibody) by transfusion orpregnancy. The anti-Hro antibody produced by RhD-- deletionmothers can react with all red blood cells expect RhD--, Rhnull andRhmod cells, resulting to destruction of fetus red blood cells and causingsevere hemolytic disease. We investigated two RhD-- deletion pregnancypatients which are occurred severe HDFN. In this study by monitoringtheir anti-Hro antibody titer and using intrauterine B-ultrasound. Weproposed application of least incompatible blood exchange transfusion onRhD-- deletion induced HDFN patients. Since one blood type iscorresponding to various genotypes, and varied in different races ordifferent population among one race. The current gene structureinformation of blood types is dissected on white people, which isinconsistent with Chinese people. Through this study, We detected thetwo RhD-- deletion individuals' serology characteristics, geneconstruction, and expression regulation, and explored the new mechanismbehind Chinese Han population RhD-- deletion disease, which providednew insights of Chinese blood type gene construction, new Rh allelesinformation, and the importance of genetyping on the RhD-- deletion individuals.Methods (1) ABO and Rh blood typing, RhD-- deletion comfirming test, Coombs' test, accident antibody screening and identification, dynamic monitor of maternity antibody title and HDFN tests were carried out in the two RhD-- deletion individuals as well as ABO/Rh blood typing on their family members. (2) One newborn patient of HDFN was applied to common medical therapy and hemolysis monitoring. The least incompatible blood exchange transfusion was performed since the antigen-negative blood was unavailable. Another newborn patient of HDFN was applied to antoblood storage, pregnancy monitoring, traditional Chinese medicine, lymphocyte plasma exchanging, intrauterine transfusion and exchange transfusion. (3) Multiple exons and introns of RHD and RHCE gene of RhD-- deletion individuals and their family members were assayed by PCR-SSP. Southern blotting was employed on HindIII and sph I digested genome DNA of two RhD--deletion individuals. RT-PCR was used to analyze the RHCE gene transcript splicing.Result (1) RhC/c, E/e antigens were complete absent in the red blood cells and anti-Hro antibody is existed in the serum of the two RhD-- deletion individuals which come from consanguineous and non-consanguineous family, respectively. The parental generation individuals are homozygote of Rh and no other RhD-- deletion patients were observed. (2) The first newborn is survived by the application of least incompatible blood exchange after unsuccessful medical therapy. The child developed normally in the four years follow-up. In the second case, although the anemia of the fetus was approved greatly and the date of pregnancy was prolonged, the newborn was born as premature infant in the 32⁺² gestation by cesarean delivery. The relatives gave up rescuing since there was no independent breath and abnormity of bowel after intensive treatment was applied to this infant. (3) Southern blotting confirmed that the exonl of RHCE gene is existed in the two RhD--deletion individuals, but the exon4-7 is deleted. PCR-SSP also found that intron4, exon4-7 are deleted, while exon3 and 9 are existed.Conclusion (1) The two pregnancy patients both are RhD--deletion which could occure in consanguineous and non-consanguineous family. (2) Severe HDFN may occur in RhD-- deletion with high probability and the least incompatibility blood exchange transfusion is an effective treatment. Enforcing monitoring and comprehensive therapy through the pregnancy is the most effective way to prevent HDFN. (3) RHCE gene exon4-7 deletion induced loss of function may contribute to the Chinese Han population RhD-- deletion. It is different from the result of mechanism of RhD-- deletion in White people and Black people.