Miltenberger class IX of the MNS blood group system

Molecular genetic analysis of Mia -positive hybrid glycophorins revealed two novel alleles of GP.Vw and multiple variant transcripts of GYPB existing in both the homozygous GP.Mur and wild-type GPB individuals

BACKGROUND

The hybrid glycophorins of MNS blood group system express a series of low incidence antigens including Mi^a , which are commonly found in Southeast Asian populations. In this study, the molecular basis of Mi^a -positive hybrid glycophorins was firstly clarified in the Chinese Southern Han population. RNA transcripts of GYPB gene in the homozygous GP.Mur individuals were also analyzed.

STUDY DESIGN AND METHODS

DNAs were extracted from the whole blood samples of 111 Mi^a -positive donors. Then, high-resolution melting (HRM) analysis for GYP(B-A-B) was used to analyze the genotypes. Sequencing of GYPB pseudoexon 3 was conducted in the samples with variant melting curves. TA-cloning and subsequent sequencing of GYPA exons 2-4 were performed in the Mi^a -positive samples with normal GYPB/GYPB genotype by HRM. The transcript analysis of GYPB was conducted in homozygous GP.Mur and wild-type glycophorin B (GPB) individuals using RNA extracted from the cultured erythroblast.

RESULTS

The heterozygous GYP*Mur/GYPB (n = 101), homozygous GYP*Mur/GYP*Mur (n = 7) including one novel GYP*Mur allele with an extra GYPA/GYPE specific nucleotide substitution (c.229+110A>T), heterozygous GYP*Bun/GYPB (n = 1) and GYP*Vw/GYPA (n = 2) with two novel GYP*Vw alleles were identified. RNA transcript analysis revealed multiple transcripts of GYPB existing in both homozygous GP.Mur and normal GPB individuals.

CONCLUSION

The results showed the genetic diversity of hybrid glycophorins in the Chinese population. Besides, the successful analysis of GYPB transcripts indicates that the cultured erythroblast is a good source for RNA transcript analysis for the protein only expressed on the red blood cells.

Novel GYP(A-B-A) hybrid gene in a DANE+ person who made an antibody to a high-prevalence MNS antigen

BACKGROUND

The glycophorin (GP) molecule associated with the GP.Dane phenotype is a GP(A-B-A) hybrid that contains some amino acids encoded by the Pseudoexon 3 of GYPB and Asn(45) of GPA and carries the low-prevalence MNS antigens DANE and Mur. Serum from a woman of English ancestry contained an immunoglobulin M alloantibody to a high-prevalence MNS antigen, and the purpose of this study was to identify the molecular basis of her phenotype.

STUDY DESIGN AND METHODS

Hemagglutination, Western blotting, and DNA analyses were performed by standard methods.

RESULTS

Tests of the proband's RBCs with monoclonal antibodies indicated a change of amino acids between positions 27 and 55 of GPA. Her RBCs expressed M, s, Mur, and DANE antigens and were M(g)-negative. The antigen recognized by her antibody was sensitive to treatment with papain, ficin, and trypsin and resistant to alpha-chymotrypsin and dithiothreitol. Sequencing of DNA from the proband revealed a sequence of nucleotides identical to the GYP(A-B-A) encoding GP.Dane but without the adenyl nucleotide substitution, which has been predicted to change Ile(46) of GPA to Asn(45). Testing of her immediate family revealed the presence of an M(k) gene.

CONCLUSION

The proband had a novel GYP(A-B-A) encoding a DANE+ GP that is in cis to GYPB(s) and in trans to M(k). The high-prevalence antigen lacking from this GP.Dane phenotype and recognized by the proband's serum is called ENDA (ISBT Number MNS44). Our results indicate that the change of Ile(46) of GPA to Asn(45) of GP.Dane is not required for expression of the DANE antigen.

Genomic typing of human red cell miltenberger glycophorins in a Taiwanese population

BACKGROUND

Antigens in the human red cell Miltenberger series are glycophorin variants of the MN (MNS) blood group system that are due to the rearrangement of glycophorin A (GPA) and glycophorin B (GPB) genes.

STUDY DESIGN AND METHODS

Taking advantage of the differences between the GPA and GPB genes, a polymerase chain reaction-based method was developed to detect all the Miltenberger glycophorin variants and St(a) subtype. GPA- and GPB-specific primers were used to amplify the GPA or GPB gene, and the amplified products were used to recognize the different hybrid genes after restriction enzyme digestions.

RESULTS

Among 264 Taiwanese subjects studied, Mi.III and St(a) are the most common types of Miltenberger variants found. Mi.III was present in 13 (4.92%) of 264, and St(a) was found in 8 (3. 03%) of 264; 1 case (0.4%) of Mi.V was also identified from the study group.

CONCLUSION

This is the first polymerase chain reaction-based method of detecting most of the Miltenberger variants and St(a). The genomic typing results were confirmed by control DNA of identified Miltenberger phenotypes. The prevalence rates of Mi. III and St(a) in this study were also consistent with other previous reports using different methods.

Miltenberger subsystem of the MNSs blood group system. Review and outlook

The Miltenberger (Mi) classes represent a group of phenotypes for red cells that carry low frequency antigens associated with the MNSs blood group system. The antigens of this system are known to be located on two sialoglycoproteins denoted as glycophorin A (GP A) and GP B. The structural alterations of seven (classes I, II, III, V, VI, VII, VIII) Mi variants and a related variant (J.L.) have been elucidated. Based on these data and yet incomplete studies of the Mi antigens, the approximate structural alterations in class IV and IX may be predicted. In addition, knowledge of the various structures and partial characterization of the Mi antigens allows one to propose detailed hypotheses concerning the epitopes recognized by the various antibodies that define the Mi subsystem. The understanding of the Mi subsystem at the molecular level paves the way for future studies aimed at a more detailed elucidation of epitopes of Mi-related antibodies, the characterization of novel Mi variants and a search for hypothetical, hitherto unknown Mi-related antibodies.