Browsing by Author "Panzer, S."

BACKGROUND: Accurate D antigen identification is essential for pretransfusion and prenatal evaluation to prevent anti-D alloimmunization. Quantitative and qualitative D variants may pose typing problems and require particular consideration because of differing potential for anti-D induction. STUDY DESIGN AND METHODS: A novel partial D, DWI, was discovered in an anti-D-alloimmunized D+ Austrian woman. This D variant was investigated by RHD genotyping and nucleotide sequencing, as well as characterization of its serologic properties. RESULTS: The proposita exhibited a single-nucleotide exchange in RHD Exon 7 (1073T>C) predicting a Met358Thr substitution in the sixth extracellular loop of the RhD polypeptide. All DWI individuals identified (the proposita and two relatives) were genotyped DWIdCcee, which, together with the family tree, was highly suggestive of a DWICe haplotype association. Epitope mapping studies revealed only minor D antigen modification with weakening but not loss of epitopes D1.1, D9.1, and D16.1. Antigen density varied individually between 8000 and 8600 D sites per erythrocyte. No known low-frequency Rh antigen was detected. Despite the highly retained D epitope composition, the DWI proposita's serum sample contained alloanti-D from an immunization event many years earlier. CONCLUSION: The findings of this investigation emphasize the possible clinical significance of "highgrade" partial D variants that are likely to be missed by routine serology.

Childhood acute lymphoblastic leukemia (ALL) Is frequently initiated in utero at a time of developmentally regulated insertion of N regions into the DJ(H) rearrangements of immunoglobulin heavy-chain (Ig(H)) genes. Here it is shown that N regions are present In the clonotypic DJ(H) rearrangements In 11 of 12 infant ALLs with t(4;11). These data are compared with the 122 previously published DJ(H) sequences and were found to have a pattern similar to that of ALL in children older than 3 years at diagnosis but were unlike that in children younger than 3 years who predominantly lack N regions. These findings, therefore, indicate that t(4;11)-positive infant ALL is initiated later in fetal development than most B-cell precursor ALL from children younger than 3 years and that they have a shorter latency period already in utero. (C) 2001 by The American Society of Hematology.

The serological differentiation of weak D from partial D, D-negative and D-positive is not always unequivocal. Therefore, sequencing of the RHD gene is required in some cases. Very recently, several new differences between RHD and RHCE have been identified which permitted us to design primers close to the exon/intron boundaries of the RHD-exons. We evaluated these primers in 83 D-positive and 18 D-negative blood donors and applied the new method for the characterization of the RHD gene in six individuals with weak D phenotype. The amplification reactions were concordant with serological findings in 100 of 101 donors (99.0%). In one D-positive donor the PCR for exons 2 and 5 gave a negative result, while the sequence of the remaining eight exons was unchanged. By sequencing samples with very weak D serological reactions, we identified weak D type 4.2.2 and weak D type 15, both previously reported to be associated with anti-D-alloimmunization. Consequently, we recommended the selection of D-negative blood in the weak D type 4.2.2 patient, and the provision of Rh prophylaxis for pregnant women with weak D type 15. In summary, a new RHD sequencing method was developed which can be applied if serological reactions are inconclusive.

BACKGROUND: The discrimination of D+/D+ from D+/D- partners of D- mothers with anti-D is important to estimate the risk for HDN. This may be achieved if the presence or absence of the hybrid Rhesus box in the father can be demonstrated. STUDY DESIGN AND METHODS: A new PCR-SSP method specific for the hybrid Rhesus box comprising an internal amplification control was compared with two published PCR-based methods (PCR-SSP and PCR-RFLP) in 83 D+, 13 D-, and 37 weak D samples. RESULTS: The deletion of RHD was detectable in all D- and weak D samples. By all three methods, concordant results were obtained in 82 of 83 D+ samples, with one sample showing discrepant results. The control band in the PCR-RFLP method, specific for the downstream Rhesus box, was missing in two weak D samples, namely a weak D type 4.0 and a novel weak D type dubbed weak D type 29. Further investigations revealed an altered downstream Rhesus box in the weak D type 29 sample. In the weak D type 4.0 sample, no amplicon was achieved with any primer specific for the upstream and downstream Rhesus box. CONCLUSION: A PCR-SSP method with internal control was established for the detection of the hybrid Rhesus box. Polymorphisms in the downstream Rhesus box may interfere with the detection of RHD.