Detection of MNS hybrid molecules in the Thai population using PCR-SSP technique.

We developed a polymerase chain reaction-sequence-specific primer (PCR-SSP) technique to screen for hybrid molecules in the MNS blood group in the Thai population using two sets of newly designed primers specific for four GYP(B-A-B) hybrids, GP.Mur, GP.Hop, GP.Bun and GP.HF, and two GYP(A-B-A) hybrids, GP.Vw and GP.Hut. One thousand and forty-one blood samples were tested with human anti-Mi(a) by conventional tube technique, and 598 samples of these were tested by the PCR-SSP technique. Ninety-four samples (9.03%) were strongly positive with human antisera by conventional tube technique. For PCR-SSP test results, the GP.Hut, GP.Mur, GP.Hop, GP.Bun and GP.HF genotypes were amplified with the first set of primers, whereas GP.Vw genotype was amplified with a second set of primers. The GYP(A-B) hybrids (GP. Hil and GP.JL), GYP(A-B-A) hybrids (GP.Nob, GP.Joh and GP.Dane), GYPA, GYPB and GYPE were not amplified by either set of primers. Results of testing 94 Mi(a+) and 504 Mi(a-) by conventional tube technique and PCR-SSP were concordant. This study shows that analysis by PCR-SSP is simple and convenient; therefore, it can be used as an alternative to conventional tube technique for mass screening for MNS hybrids, especially when specific antisera are not available.

Review: molecular basis of MNS blood group variants.

The MNS blood group antigens are expressed in the RBC membrane on glycophorin A (GPA), glycophorin B (GPB), or combinations of both. GPA expresses the M or N antigen, whereas GPB expresses the S or s antigen and the N antigen ('N'). Both glycophorin genes (GYPA and GYPB) are located on the long arm of chromosome 4 and share 95 percent sequence identity. This high degree of sequence identity, together with the rare involvement of a third homologous gene (GYPE), provides an increased chance of recombination, resulting in hybrid molecules that often carry one or more novel antigens. Some of the antigens in the MNS system result from a single nucleotide substitution. The MNS blood group system now consists of more than 40 distinct antigens. This review summarizes the molecular basis associated with some of the antigens in the MNS blood group system.

Analysis of SERF in Thai blood donors.

The Cromer blood group system consists of nine high-prevalence and three low-prevalence antigens carried on decay-accelerating factor (DAF). We recently described one of these Cromer highprevalence antigens,SERF, the absence of which was found in a Thai woman. The lack of SERF antigen in this proband was associated with a substitution of nucleotide 647C>T in exon 5 of DAF, which is predicted to be a change of proline to leucine at amino acid position 182 in short consensus repeat (SCR) 3 of DAF. This study reports on PCR-RFLP analysis of the SERF allele with BstNI restriction endonuclease on more than one thousand Thai blood donor samples. One new donor homozygous (647T) and 21 donors heterozygous (647C/T) for the SERF allele were found. Among this cohort of random Thai blood donors, the SERF allele frequency was 1.1 percent. Thus, like other alleles in the Cromer blood group system, SERF is found in a certain ethnic group.

SERF: a new antigen in the Cromer blood group system.

The Cromer blood group system consists of eight high incidence and three low incidence antigens carried on decay-accelerating factor (DAF). This report describes the identification and characterization of a new Cromer high incidence antigen, named SERF. Sequence analyses of DNA from a Thai female whose serum contained the alloantibody to a high incidence antigen in the Cromer blood group system (anti-SERF) and from her two children were performed. Reverse transcriptase-polymerase chain reaction (RT-PCR) and sequence analysis on cDNA from the proband and PCR-restriction fragment length polymorphism analysis on DNA from Thais were also performed. To map the epitope, DAF deletion mutants were tested by immunoblotting with anti-SERF. Sequence analysis revealed a substitution of 647C>T in exon 5 DAF in the proband. The proband's two children and two of 100 Thais were heterozygotes 647C/T. Analysis using DAF deletion mutants revealed the antigenic determinant to be within short consensus repeat 3 (SCR3), which is encoded by exon 5. This study describes a novel high incidence antigen (SERF) in the Cromer blood group system characterized by the amino acid proline at position 182 in SCR3 of DAF. The SERF-negative proband has a substitution mutation that predicts for leucine at this position. SERF has been provisionally assigned the International Society of Blood Transfusion number 021.012 (CROM 12).