Genotyping analysis of the MNS blood group system of thalassemia patients with alloantibodies in Iran

BACKGROUND

Serological methods are unreliable for accurate determination of blood group antigens in multi-transfused thalassemia patients. The MNS blood group system has five high-frequency antigens. Many studies demonstrated that some antibodies including anti-S, anti-s, and anti-U may cause acute and delayed transfusion reactions and hemolytic disease of the fetus and newborn. This study aimed to determine the genotype of the MNS blood group in thalassemia patients with alloantibodies by molecular methods.

MATERIAL AND METHODS

In this study, 104 blood samples from thalassemia patients were collected. The blood group phenotype for M, N, S and s antigens was determined by the tube hemagglutination method. MNS blood group genotyping was performed using PCR-SSP and DNA Sequencing methods.

RESULTS

All patients were genotyped with a total of 6 pairs of primers. Discrepancies between genotype and phenotype were observed in 22 patients with S/s alleles and 2 patients with M/N alleles, however, there was full accordance between the results of SSP-PCR and DNA sequencing. The frequency of MNS blood group alleles was determined as follows: 25 % MNSs, 23 % MNss, 21 % MMSs, 9% MMSS, 9% MMss, 8% NNss, 2%MNSS, and NNSS, NNSs, MM genotypes at 1% each.

CONCLUSION

In conclusion, molecular genotyping is more reliable than serological methods in multiple transfusion patients and can lead to a more compatible blood unit for transfusion in these patients.

Intrauterine development and MNSs blood groups in repeated spontaneous abortion

OBJECTIVES

To determine whether the maternal MNSs genotype has an effect on the birth weight and gestation duration of the live offspring of women with repeated primary spontaneous abortion (RSA).

METHODS

The study sample consisted of 239 healthy white women who had been delivered of a live infant, and 137 women with a history of primary RSA-54 of whom had recently been delivered of a live infant and 83 who had had a spontaneous abortion. Maternal MNSs phenotypes were determined by standard serological methods, and the results were analyzed for relationships between these phenotypes and the mothers' reproductive status and the infants' birth weight and gestational age. Analysis of variance, the chi(2)-test of independence, and the Mantel-Haenszel test for linear association were performed for data analysis.

RESULTS

Infants born to mothers with the Ss genotype showed significantly lower birth weight and gestational duration compared with the infants of mothers with other genotypes. Additionally, the MNSs haplotype was found to be associated with birth weight.

CONCLUSIONS

Previous studies have shown that the MNSs system influences the gestational age of aborted fetuses in cases of RSA. The present study supports the hypothesis that this genetic factor influences intrauterine growth and development in women experiencing RSA.

The identification of a victim using the DGGE method for trace deposits collected on adhesive film

The denaturant gradient gel electrophoresis (DGGE) method was used in order to simultaneously estimate the genotypes of different factors in a gel plate consisting of one sheet. A genotype analysis of the blood groups (MN, Duffy, Kidd type) and serotype (Gc system) was carried out. DNA samples were extracted from trace deposits which were transferred on adhesive film from a blood trace obtained from a car tire after a fatal car accident. The reference DNA was prepared from the victim's blood. The PCR amplification fragments were amplified from the gene which controlled each blood group. The primers were designed in order to analyze the genotypes with one to three base substitutions in the amplification product. The denaturant concentration limit of the gel for the DGGE method to detect each genotype of the blood groups (MN, Duffy, Kidd type and Gc system) and other conditions of electrophoresis were performed according to previously methods. The each genotype of the blood groups and the Gc system were all simultaneously distinguished in one plate.

Efficient chemoenzymatic synthesis of O-linked sialyl oligosaccharides

The tumor associated Tn (GalNAcalpha(1-1)-Thr/Ser)- and T (Galbeta(1-3)-GalNAcalpha(1-1)Thr/Ser)-antigens and their sialylated derivatives are present on the surface of many cancer cells. Preparative synthesis of these sialylated T- and Tn-structures has been achieved mainly from a chemical synthetic approach due to the lack of the required glycosyltransferases. We demonstrate a flexible and efficient chemoenzymatic approach for using recombinant sialyltransferases including a chicken GalNAcalpha2,6-sialyltransferase (chST6GalNAc I) and a porcine Galbeta(1-3)GalNAcalpha-2,3-sialyltransferase (pST3Gal I). Using these enzymes, the common O-linked sialosides Neu5Acalpha(2-6)GalNAcalpha(1-1)Thr, Galbeta(1-3)[Neu5Acalpha(2-6)]GalNAcalpha(1-1)Thr, Neu5Acalpha(2-3)Galbeta(1-3)GalNAcalpha(1-1)Thr, and Neu5Acalpha(2-3)Galbeta(1-3)[Neu5Acalpha(2-6)]GalNAcalpha(1-1)Thr were readily prepared at preparative scale. The chST6GalNAc I was found to require at least one amino acid (Thr/Ser) for optimal activity, and is thus an ideal catalyst for synthesis of synthetic glycopeptides and glycoconjugates with O-linked glycans.

Molecular evolution of alleles of the glycophorin A gene

Highly-homologous Glycophorin A (GPA), B and E genes are triplicate genes, and involve many subtypes and minor antigens constructing the Miltenberger subsystem. These genes and most of the variants are hypothesized to arise by recombination, because hot spots are located in the gene sequences. By sequencing exons 1-7 and introns 1-3 of standard alleles of GPA gene, M and N alleles were classified into six variations: provisionally called MN*M101, M102, M201, M202, N101 and N102 in our previous study. Here we further investigated the sequences of introns 4-6 using GPA gene-specific primers and by DNA sequencing, and found eight, five and nine new nucleotide substitutions or deletions in introns 4, 5 and 6, respectively. Using the computer program PHYLIP 3.5, the phylogenetic trees were reconstructed. Phylogenetic analysis of the allele sequences revealed that M200s alleles arose from M101 after the separation of M101 and N101 and branched to M201 and M202 via the accumulation of point mutations. M102 and N102 alleles were estimated to generate via recombination between M101 and N101 occurred around the hot spot. The findings also suggested the existence of other GPA variants with normal antigenicity, and are quite useful in the forensic and anthropological fields.