RHCE*ceAR encodes a partial c (RH4) antigen.

Thr Rh blood group system is highly complex both in the number of discreet antigens and in the existence of partial antigens, especially D and e. Recently, several partial c antigens have been reported. Here we report findings on an African American man with sickle cell disease whose RBCs typed C+c+ and whose plasma contained anti-c. Hemagglutination tests, DNA extraction, PCR-RFLP, reticulocyte RNA isolation, RT-PCR cDNA analyses, cloning, and sequencing were performed by standard procedures. RBCs from the patient typed C+c+ but his plasma contained alloanti-c. DNA analyses showed the presence of RHCE*Ce in trans to RHCE*ceAR with RHD*D and RHD*Weak D type 4.2.2. The amino acid changes on RhceAR are such that C+c+ patient made alloanti-c. This case shows that RhceAR carries a partial c antigen and illustrates the value of DNA testing as an adjunct to hemagglutination to aid in antibody identification in unusual cases.

The low prevalence Rh antigen Be(a) (Rh36) is associated with RHCE*ce 662C>G in exon 5, which is predicted to encode Rhce 221Arg.

BACKGROUND AND OBJECTIVES: The low prevalence antigen, Be(a), is produced by a complex that also produces weak c, e and f (ce). We report here the molecular basis associated with Be(a) antigen expression. MATERIALS AND METHODS: Peripheral blood samples from four Be(a+) probands were tested. Haemagglutination, gDNA extraction, PCR-based assays, reticulocyte RNA isolation, Rh-cDNA analyses, and sequencing were performed by standard procedures. RESULTS: RBCs from Probands 1 and 3 were D-C-E-c+e+, and from Probands 2 and 4 were D+C+E-c+(W)e+. In proband 1, cDNA sequencing of RHCE revealed heterozygosity of nucleotide (nt) 662C/G in exon 5 of RHCE*ce. No other nucleotide changes were observed. As the 662C>G nucleotide change ablates a MscI restriction enzyme cleavage site, PCR-RFLP analysis was performed and the RHCE*ce nt 662C/G heterozygosity was detected on gDNA from the four probands and two children from both Proband 3 and Proband 4. CONCLUSION: The low prevalence Rh antigen, Be(a), is associated with a single nucleotide change in exon 5 of RHCE*ce; that of 662C>G and this change is predicted to alter proline at amino acid position 221 of Rhce to arginine. The fundamental differences in the properties of these two amino acids may impose a steric and/or charge-related effect on the protein, and thereby provide an explanation for the weakened expression of c, e and f (ce) antigens in the Be(a) phenotype.

The polymorphism nt 76 in exon 2 of SC is more frequent in whites than in blacks.

The Scianna blood group system comprises seven antigens encoded by alternative forms of SC. The SC gene also has two polymorphisms in the leader sequence, at nucleotides 54 (C/T, silent) and 76 (C/T, 26His/Tyr) in exon 2, which are not involved in expression of blood group antigens. The nucleotide change at position 76 has an NlaIII restriction enzyme site; thus, DNA samples from 100 Caucasians and 100 African Americans were analyzed for the SC nucleotide 76 change. DNA from Caucasian and African American donors was tested by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) using the restriction enzyme NlaIII. In selected samples, sequencing of exon 2 was performed. PCR-RFLP results for samples from 100 donors (mostly Caucasian) and 100 African American donors (400 alleles) showed the nucleotide 76T variant had a prevalence of 25 percent in Whites and 5 percent in African Americans. In 11 samples (2 C/C, 3 C/T, and 6 T/T) sequencing of exon 2 confirmed the presence of the expected nucleotides at position 76. The allele frequency in Caucasians was 0.75 for nt76C and 0.25 for nt76T. In African Americans, the frequencies were, respectively, 0.95 and 0.05.

Excess syncytiotrophoblast microparticle shedding is a feature of early-onset pre-eclampsia, but not normotensive intrauterine growth restriction.

RATIONALE: Syncytiotrophoblast microparticles (STBM) are shed into the maternal circulation in higher amounts in pre-eclampsia compared to normal pregnancy and are believed to be the stimulus for the systemic inflammatory response and endothelial cell damage which characterises the maternal syndrome. The excess shedding of STBM may be caused by hypoxia as a result of poor placentation, which is often a feature of pre-eclampsia. Similar placental pathology occurs in some cases of normotensive intrauterine growth restriction (nIUGR), but in the absence of maternal disease. OBJECTIVE: To examine whether the shedding of STBM in nIUGR occurs to the same extent as in pre-eclampsia. METHODS: A prospective case-control study in a tertiary referral centre of: 1) women with early-onset pre-eclampsia (EOPET < 34 week), 2) women with late-onset pre-eclampsia (LOPET > or = 34 week), 3) women with nIUGR), 4) matched normal pregnant women (NPC), and 5) non-pregnant women. An ELISA using the antitrophoblast antibody NDOG2 was used to measure STBM levels in peripheral venous plasma. Non-parametric analyses were conducted with statistical significance set at p < 0.05. RESULTS: STBM levels rise during normal pregnancy. EOPET was associated with increased STBM levels (EOPET (median): 41 ng/ml, n = 15) compared with matched normal pregnancy (16 ng/ml, n = 15; Wilcoxon p = 0.005). LOPET (50 ng/ml, n = 10) and nIUGR (18 ng/ml, n = 8) STBM levels did not differ from matched normal pregnancy (36 ng/ml, n = 15, and 36 ng/ml, n = 8, respectively). Background levels in non-pregnant plasma were 0.49 ng/ml, n = 10. CONCLUSIONS: Increased STBM levels were found in EOPET but not in nIUGR providing further evidence for their role in the pathogenesis of the maternal syndrome.