Genotipificación del gen RHD en ADN fetal libre en plasma de embarazadas RhD negativo / Genotyping of the RHD gene in free fetal DNA in plasma of RhD negative pregnant women

Objetivo: Determinar el grupo RhD fetal a través del estudio del gen RHD en ADN fetal que se encuentra libre en plasma de embarazadas RhD negativo. Método: Se analizó la presencia de los genes RHD, SRY y BGLO en ADNfl obtenido de plasma de 51 embarazadas RhD negativo no sensibilizadas, utilizando una qPCR. Los resultados del estudio genético del gen RHD se compararon con el estudio del grupo sanguíneo RhD realizado por método serológico en muestras de sangre de cordón, y los resultados del estudio del gen SRY fueron cotejados con el sexo fetal determinado por ecografía. Se calcularon la sensibilidad, la especificidad, los valores predictivos y la capacidad discriminativa del método estandarizado. Resultados: El gen RHD estaba presente en el 72,5% de las muestras y el gen SRY en el 55,5%, coincidiendo en un 100% con los resultados del grupo RhD detectado en sangre de cordón y con el sexo fetal confirmado por ecografía, respectivamente. Conclusiones: Fue posible deducir el grupo sanguíneo RhD del feto mediante el estudio del ADN fetal que se encuentra libre en el plasma de embarazadas con un método molecular no invasivo desarrollado y validado para este fin. Este test no invasivo puede ser utilizado para tomar la decisión de administrar inmunoglobulina anti-D solo a embarazadas RhD negativo que portan un feto RhD positivo.

Objective: To determine the fetal RhD group through the study of the RHD gene in fetal DNA found free in plasma of RhD negative pregnant women. Method: The presence of the RHD, SRY and BGLO genes in fetal DNA obtained from plasma of 51 non-sensitized RhD negative pregnant women was analyzed using qPCR. The results of the genetic study of the RHD gene were compared with the RhD blood group study performed by serological method in cord blood samples, and the results of the SRY gene study were compared with the fetal sex determined by ultrasound. Sensitivity, specificity, predictive values and discriminative capacity of the standardized method were calculated. Results: The RHD gene was present in 72.5% of the samples and the SRY gene in 55.5%, coinciding 100% with the results of the RhD group detected in cord blood, and with the fetal sex confirmed by ultrasound, respectively. Conclusions: It was possible to deduce the RhD blood group of the fetus through the study of fetal DNA found free in the plasma of pregnant women with a non-invasive molecular method developed and validated for this purpose. This non-invasive test can be used to make the decision to administer anti-D immunoglobulin only to RhD-negative pregnant women carrying an RhD-positive fetus.

Molecular basis of RhD-negative phenotype in North Indian blood donor population

Background & objectives: RHD gene typing is highly complex due to homology with RHCE genes. Molecular polymorphism of the RHCE and RHD genes have been characterized among various populations, but no studies have been undertaken among Indians. This study was undertaken to assess the genetic basis of RHD-negative phenotype in Indian blood donor population. Methods: Sample from a total of 200 phenotypically RhD-negative blood donors were analyzed for presence of RHD gene using polymerase chain reaction (PCR). RHD genotyping was done using three primer sets designed for exons 4 and 10 and one set for identification of pseudo (RHD?) gene between introns (int) 3 and 4. Amplified PCR products were analyzed by gel-electrophoresis (XY Loper, Uvitech, Cambridge) and confirmed by nucleotide sequencing (ABI 3730 xl 96 capillary system). Results: No PCR product was found in 195/200 (97.5%) of study samples indicating homozygous gene deletion. Of the 5/200 (2.5%) showing RHD gene polymorphisms, 4/200 (2%) were positive for presence of exon 10 only (RHD-CE-D hybrid). RHD? gene was not detected in any of the samples tested. One sample showed presence of all three tested regions and was negative for RHD? gene. Interpretation & conclusions: RHD gene deletion was found to be the most common cause of an RHD-negative phenotype while RHD? gene was, reported to be present in up to 39 per cent of various ethnic populations, but was not detected. RHD-CE-D hybrid gene (found in 2.5% individuals) is important for predicting the requirement of Rh prophylaxis during the antenatal period.

Phenotype and RHD gene polymorphism of 64 Rh negative individuals / 中国输血杂志

【Objective】 To collect blood samples of 64 RhD negative patients in our hospital for RHD genotyping and phenotype analysis (RhC/c/E/e), and analyze the distribution characteristics of different RHD genotypes. 【Methods】 The RHD gene of RhD negative patients was genotyped by fluorescence quantitative polymerase chain reaction (PCR) method. The Rh phenotype was identified by IgM anti-e, anti-c, anti-C and anti-E, respectively. 【Results】 Forty-two cases of RHD deletion were detected, dominated by ccee phenotype (88.1%); 9 of RHD1227A cases, dominated by Ccee phenotype(77.8%); 8 of RHD-CE(3-9)-D2 cases, dominated by Ccee phenotype (75%); 1 of RHD-CE(3-10)-D2 case with Ccee phenotype, 1 of RHD*711delC case; 1 of RHAG site invalid type were detected. The typing results could not be determined in 2 cases by PCR method. 【Conclusion】 RhD negative patients showed diversity in RHD genotype, dominated by RHD deletion, followed by RHD1227A, RHD-CE(2-9)-D2, RHD-CE(3-10)-D2, RHD*711delC and RHAG site deletions.

Molecular mechanism and bioinformatics analysis of 9 samples with rare RhD variants / 中国输血杂志

【Objective】 To study the molecular mechanism of 9 samples with rare RhD variants and their RhD epitopes and protein structure. 【Methods】 The 9 blood samples with rare RhD variants were collected from 210 644 blood donors of Shenzhen Blood Center. Regular serological assaying was used for determination of Rh type for the 9 samples. Indirect anti-human globulin test (IAT) was used to confirm the RhD antigen and to screen the antibodies. D-screen reagent was sued to analyze the RhD epitopes of the samples. RHD zygosity testing of the samples was detected by PCR-SSP. The nucleotide sequences of all 9 exons and adjacent flanking intron regions of RHD gene were sequenced. The prediction of the effects of mutations on RhD protein function were analyzed using PROVEAN, SIFT, PolyPhen-2 and MutationTaster software. Robetta and Swiss-PdbViewer 4.1.0 were used for modeling the tertiary structures of RhD. 【Results】 A total of 9 individuals with rare RhD variants were identified as follows: RHD*weak D type 25, RHD*weak D type 50, RHD*weak D type 95, RHD*weak D type 12, RHD*weak D type 128 and four novel RHD alleles. The prediction of the tertiary structures showed that the RhD protein conformation was disrupted in the 9 rare RhD variants samples. 【Conclusion】 Five rare and four novel RHD alleles have been identified. Their phenotypic and genotypic descriptions enrich the database of reported RHD alleles. Bioinformatics analysis provided evidences for further study of the structure and functions of RhD protein.

Genetic background of RhD negative blood donors / 中国输血杂志

【Objective】 To analyze the genetic background of RhD-negative blood donors by detecting RHD and RHCE genes of those donors. 【Methods】 From March 2021 to May 2022, the blood samples of RhD-negative blood donors, who had been screened out by RhD primary screening and confirmatory experiments in the Yaan Blood Center, were firstly identified whether the RHD allele was completely deleted, then whether there were deletions in 10 exons of non-RHD allele complete deletion samples, finally, the remaining samples without RHD alleles and exon deletions were further analyzed by DNA sequencing. RHCE gene was detected by SSP-PCR method. 【Results】 Among the RHD gene test results of 104 RhD-negative samples, 65 cases were completely deleted (d/d), 33 were RHD partially deleted (one allele deletion), and 6 were without RHD gene deletion. The RHD alleles of 33 samples with partial deletion were detected by 10 exons, 13 had partial exon deletion, with genotype as RHD*D-CE(3-9)-D/d and phenotype as RhD negativity, and the remaining 20 samples had no exon deletion. The exon sequencing results of the non-deletion samples showed RHD*1227A/RHD*1227A in 6 samples, RHD*1227A/d in 19, RHD*3A/d in 1; both of the last two were considered Del by ISBT. The RHCE gene test results showed that all cc genotype blood donors were RhD true negative, while Del blood donors had no cc genotype. 【Conclusion】 Through the genetic background study of RhD negative blood donors, it is found that there is a high proportion of Del with weak expression of RhD antigen, whether this blood type affects clinical blood safety needs further researches.

Frequency analysis of RHD*1227A allele among Rh negative Han population and random population in Liaoning / 中国输血杂志

【Objective】 To investigate the frequency of RHD*1227A allele in Rh negative Han polulation and random population in Liaoning. 【Methods】 Del phenotype was screened by absorption-elution test, the RHD*1227A allele was screened by PCR-SSP and confirmed by nucleotide sequence analysis of RHD full coding region, and the heterozygosity of RHD gene was detected by hybridization technique. 【Results】 24 case of Del phenotype were detected by the absorption-elution test among 117 Rh negative individuals. 23 RHD*1227A allele carriers were detected by PCR-SSP and sequencing-based typing (SBT). Genotype of 19 individuals was RHD*1227A/RHD*01N.01, while the other 4 was homozygous RHD*1227A/ RHD*1227A.11 individuals were detected as RHD*1227A allele among 1 045 random blood donors, among which 9 were RHD*1227A/RHD*01 and 2 were RHD*1227A/RHD*01N.01. 【Conclusion】 The frequency of RHD*1227A allele is 0.115 4 in Rh negative Han population and 0.005 3 in random population in Liaoning..

Identification of two novel weak D alleles by sequence-based typing / 中国输血杂志

【Objective】 To study the molecular basis of D variant and explore the molecular genetic mechanism of novel weak D alleles. 【Methods】 Blood samples were screened for D variants by serological method. The nucleotide sequences of coding region were amplified by PCR and sequenced directly, and RHD gene heterozygosity was detected. 【Results】 Weak D phenotype was confirmed by serological test, and two novel alleles were detected by DNA sequencing. The first was novel weak D 1102A allele, 1102G>A mutation in exon 8, resulting in a 368Glu>Arg substitution in two samples. The second was novel weak D 399C allele, carried a 399G>C mutation in exon 3, which led to a 133Lys>Asn substitution. 【Conclusion】 In this study, D variants were detected by sequence-based typing, and two new alleles were identified.

Molecular biologicalstudy of DEL in RhD-negative blood donors, Dalian / 中国输血杂志

【Objective】 To study the frequency, Rh phenotypes and molecular & biological background of D-elute (Del) phenotype in RhD-negative blood donors in Dalian. 【Methods】 A total of 355 serologically RhD-negative samples between November, 2018 and October, 2019 in Dalian Blood Center were collected, and tested for RhC, c, E, e phenotypes using monoclonal antibodies and anti-D adsorption/elution test. DNA was extracted by magnetic bead selection. RHD 1227G>A mutation was detected by melting curve analysis. All RHD exons were sequenced by Sanger sequencing. 【Results】 Among 355 serologically RhD-negative blood donors, 55 (15.5%) were identified as Del and the remaining 300 cases (84.5%) were true RhD negative. Ccee (45/55, 81.8%) was the predominant Rh phenotype among 55 Del cases while ccee (210/300, 70.0%) was the most prevalent Rh phenotypes in 300 true RhD negative cases. In 55 Del cases, 51 (92.7%) had RHD 1227G>A mutation, and the other 4 cases(7.3%) had mutations in other sites. 【Conclusion】 The frequency of Del was 15.5% in serologically RhD-negative blood donors in Dalian, with Ccee being the most prevalent Rh phenotype and RHD 1227G>A the most common gene mutation.

-D- phenotype screening by polybrene method / 中国输血杂志

【Objective】 To develop a novel screening reagent for -D- phenotype preliminary screening based on the difference in RhD antigen expression level of -D- phenotype and normal RhD phenotype. 【Methods】 RhD antigen expression of -D-phenotype and Rh D-- gene carrier were detected by flow cytometry. By adjusting the concentration of polybrene in the screening system, the red blood cells with high RhD antigen expression level agglutinated, and the preliminary screening of the -D-phenotype and its gene carriers was realized. 【Results】 According to the quantitative results of immunofluorescence intensity (MFI) analysis by flow cytometry, the expression level of RhD antigen in -D- phenotype cells (284 360±16 698, n=3) was about 3 times normal RhD positive cells (98 642±35 908, n=9)(P<0.01), while RhD antigen expression level of RhD-- gene carrier (181 109±39 455, n=4) was about 2 times normal RhD positive cells(P<0.01). RhD antigen expression (144 538±227 445, n=7) of the positive cells screened by 15 μL 3% fresh red blood cell suspension and screening system 35 μL (1 μL IgG anti-D, 29 μL polybrene polybrene, and 5 μL low ionic strength solution) was about 1.5 times normal RhD positive cells. 【Conclusion】 The polybrene preliminary screening system, which can be used for high-throughput screening of -D- phenotype, is a reliable technical method for frequency study of this phenotype.

A case study of severe hemolytic disease with the newborn caused by DⅣb type of RhD variant / 中华微生物学和免疫学杂志

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 .

RHD genotyping for the Chinese / 中国输血杂志

Objective To establish a RHD genotyping method specific for the Chinese. Methods Six pairs of primers specific for most alleles found in the Chinese according to the records in NCBI GenBank, were designed, and a multi-tube sequence-specific primer PCR (PCR-SSP) method was established with a pair of internal control primer in each reaction. The method was evaluated with samples serologically determined and full length RHD sequenced from 89 Rh-negative, 28 D el, and 13 Rh-positive, weak D and partial D phenotype of Chinese Hans. Furthermore, 318 random samples from blood donors were genotyped and the results were compared with serological results of those samples. Results The PCR-SSP results were in concordance with serological results (100%) in all samples, and all RHD positive, D antigen negative alleles (or nonfunctional alleles) observed in the Chinese up to now could be detected or implicated, including D el phenotype especially D el allele existing in Rh-positive individuals (RHD/RHD1227A). This genotype was detected with a rate of 8/318, and allele frequency should be 0.012579 Conclusion Our method is rapid and easy, with high accuracy in the testing of the Chinese.