Silent KEL alleles identified from Japanese individuals with the Ko phenotype

BACKGROUND AND OBJECTIVE

The rare K_o phenotype lacks all 36 antigens in the Kell blood system. The molecular basis of the K_o phenotype has been investigated, and more than 40 silent KEL alleles are reported by many investigators. The majority of silent alleles are the KEL*02 background. Here, we report molecular genetic analysis of the KEL gene in Japanese individuals with the K_o phenotype.

MATERIALS AND METHODS

The K_o phenotype was screened from Japanese blood donors for several years using monoclonal anti-Ku or anti-K14 by an automated blood grouping system PK7300. Kell-related antigens were typed by standard tube tests. Genomic DNA was extracted from the blood samples, and KEL gene was analysed by polymerase chain reaction (PCR) and Sanger sequencing.

RESULTS

We collected 35 K_o blood samples with K-k-, Kp(a-b-), Js(a-b-) and K14-. PCR and sequence analysis revealed that 11 individuals were homozygous for a mutant KEL allele with a c.299G>C (p.Cys100Ser) mutation (rs. 200268316). Three individuals were homozygous for the KEL*02N.24 allele that is c.715G>T (p.Glu239*), and one individual was homozygous for the KEL*02N.40 allele that is c.1474C>T (p.Arg492*). Five individuals were homozygous for novel KEL alleles with single-nucleotide mutations, four individuals had a c.2175delC (p.Pro725 fs*43), and one individual had a c.328delA (p.Arg110 fs*79). The remaining 15 individuals were compound heterozygous, and eight new alleles were identified from them.

CONCLUSIONS

We identified three known and ten new silent KEL alleles from Japanese individuals with the K_o phenotype. The KEL allele with the c.299G>C (p.Cys100Ser) mutation was the most frequent.

Production of human monoclonal anti-Jk3, recognising an epitope including the Jk(a) /Jk(b) polymorphic site of the Kidd glycoprotein

BACKGROUND AND OBJECTIVES

The Kidd blood group system consists of polymorphic antigens, Jk(a) (JK1) and Jk(b) (JK2), and a high-incidence antigen, Jk3. Anti-Jk3 is often observed in immunised Jk(a-b-) individuals. In this study, we aimed to establish a human hybridoma cell line secreting monoclonal anti-Jk3 (HIRO-294).

MATERIALS AND METHODS

Peripheral blood lymphocytes of a Filipino woman with the Jk(a-b-) phenotype having anti-Jk3 were transformed with Epstein-Barr virus and then hybridised with the myeloma cell line JMS-3 using the polyethylene glycol (PEG) method. The reactivity and specificity of the anti-Jk3 were examined by serology and flow cytometry.

RESULTS

Four hybridoma clones secreting anti-Jk3 were established and the antibody from one of these clones, HIRO-294, was examined. The reactivity of HIRO-294 was positive with 227 Jk(a+b-) red blood cells (RBCs), 298 Jk(a-b+) RBCs, and 1043 Jk(a+b+) RBCs, but was negative with 21 Jk(a-b-) RBCs. Eluates from Jk(a+b-) RBCs and Jk(a-b+) RBCs sensitised with the anti-Jk3 were cross-reacted with Jk(a-b+) RBCs and Jk(a+b-) RBCs, respectively. The reactivity of HIRO-294 was enhanced by the treatment of RBCs with ficin, trypsin, pronase and α-chymotrypsin, but was not changed by their treatment with neuraminidase, dithiothreitol and ethylenediaminetetraacetic acid (EDTA) glycine acid (GA). The RBCs sensitised by the anti-Jk3 were not agglutinated with the commercial reagents of anti-Jk(a) and anti-Jk(b) by saline test, whereas the nonsensitised RBCs or those sensitised by monoclonal anti-D [HIRO-3, immunoglobulin G (IgG) class] were agglutinated with those reagents.

CONCLUSIONS

We established a human hybridoma cell line secreting monoclonal anti-Jk3 (HIRO-294). This antibody had unique specificity, recognising the Kidd glycoprotein including the Jk(a) /Jk(b) polymorphic site.

JK null alleles identified from Japanese individuals with Jk(a−b−) phenotype

The Kidd blood group system consists of three common phenotypes: Jk(a+b−), Jk(a−b+) and Jk(a+b+), and one rare phenotype, Jk(a−b−). Jka/Jkb polymorphism is associated with c.838G>A (p.Asp280Asn) in exon 9 of the JK (SLC14A1) gene, and the corresponding alleles are named JK*01 and JK*02. The rare phenotype Jk(a−b−) was first found in a Filipina of Spanish and Chinese ancestry, and to date, several JK null alleles responsible for the Jk(a−b−) phenotype have been reported. We report seven novel JK null alleles, 4 with a JK*01 background and 3 with a JK*02 background, identified from Jk(a−b−) Japanese.

Deletion of the RUNX1 binding site in the erythroid cell-specific regulatory element of the ABO gene in two individuals with the Am phenotype

BACKGROUND AND OBJECTIVES

An erythroid cell-specific regulatory element, referred to as the +5·8-kb site, had been identified in the first intron of the human ABO blood group gene. Subsequent studies revealed that either a 5·8-kb deletion including the +5·8-kb site or disruption of a GATA factor binding motif at the site was present in all Bm and ABm individuals examined. We investigated the molecular mechanism of the Am phenotype, which is analogous to the Bm phenotype.

MATERIALS AND METHODS

Genomic DNAs were prepared from peripheral blood of two Am individuals, and the nucleotide sequences were investigated using PCR and direct sequencing. Electrophoretic mobility shift assay (EMSA) and promoter assay with K562 cells were carried out.

RESULTS

A novel 23-bp nucleotide deletion was found at the +5·8-kb site in both individuals. EMSAs demonstrated binding of the transcription factor RUNX1 to the nucleotides within the deletion. Promoter assays showed that the deletion reduced the transcriptional activity of the +5·8-kb site.

CONCLUSION

Deletion of the 23-bp nucleotides including the RUNX1 binding site decreases transcription of the A allele, resulting in the reduction in A antigen expression in the Am phenotype.

A new blood group system, RHAG: three antigens resulting from amino acid substitutions in the Rh-associated glycoprotein

BACKGROUND AND OBJECTIVES

Rh-associated glycoprotein (RhAG) is closely associated with the Rh proteins in the red cell membrane. Two high frequency antigens (Duclos and DSLK) and one low frequency antigen (Ol(a)) have serological characteristics suggestive of expression on RhAG.

MATERIALS AND METHODS

RHAG was sequenced from the DNA of one Duclos-negative, one DSLK-negative, and two Ol(a+) individuals. Recombinant protein was expressed in HEK 293 cells. Protein models with RhAG subunits were constructed.

RESULTS

The original Duclos-negative patient was homozygous for RHAG 316C>G, encoding Gln106Glu. HEK 293 cells expressing Gln106Glu mutant RhAG did not react with anti-Duclos. An individual with DSLK-negative red cells was homozygous for 490A>C, encoding Lys164Gln. Two Ol(a+) members of the original Norwegian family were heterozygous for 680C>T, encoding Ser227Leu. A Japanese donor with Rh(mod) phenotype had Ol(a+) red cells and was homozygous for 680C>T.

CONCLUSION

The three red cell antigens encoded by RHAG form the RHAG blood group system: Duclos is RHAG1 (030001); Ol(a) is RHAG2 (030002); and DSLK is provisionally RHAG3 (030003).

E variants found in Japanese and c antigenicity alteration without substitution in the second extracellular loop

BACKGROUND

The molecular basis of E variants in the Japanese population is poorly understood. In this study, molecular analysis of E variants detected in Japanese by serologic methods was carried out.

STUDY DESIGN AND METHODS

E variants from healthy Japanese blood donors were screened by serologic analysis using E MoAbs. Fifteen E variant samples were divided into three types--EFM, EKH, and EKK-on the basis of patterns of reactivity with five distinct E antibodies. The entire coding region of the Rh cDNAs from the E variant samples was analyzed by sequencing.

RESULTS

Although the Rh cDNA sequences of the three types were different from each other, those of the EFM-type variants (RHEFM) had a partial DNA exchange in exon 5 between the RHCE and RHD genes, generating an RHcE variant (Gln233Glu, Met238Val). The cDNA of EKH-type variants (RHEKH) exhibited a point mutation (G461C) in exon 3 of the RHcE allele that resulted in an Arg154Thr substitution in the third external loop of the RhcE peptide. The EKK-type variant (RHEKK) carried a hybrid gene structure characterized by replacement of exons 1-3 (or 2-3) of the RHCE gene with those of the RHD gene. The RHD gene of a person possessing an E variant of the EKK type was also a hybrid gene, D-cE(2-3)-D or cE(1-3)-D (RHDKK). The E variants of types EKH and EKK showed weak c antigenicity.

CONCLUSION

In serologic screening of 140,723 Japanese blood donors, 15 were found to possess E variants (0.011%). A new RHCE variant, RHEKH, was identified. On the basis of the variants found in this study, the c antigenicity seemed to be determined not only by Pro-103 but also by the structure of the third extracellular loop or the amino acids contained in it.

Three episodes of delayed hemolytic transfusion reactions due to multiple red cell antibodies, anti-Di, anti-Jk and anti-E

There is no report in which three episodes of delayed hemolytic transfusion reaction (DHTR) occurred from multiple antibodies to red cells (RBCs) in the course of treatment of a patient. This paper describes episodes of anemia and hyperbilirubinemia in concert with the development of three alloantibodies in a multiple transfused patient. The patient was a 71-year-old male suffering from valvular heart disease and hemophilia B with a history of transfusions. Although he received compatible RBCs from 14 donors as judged by a crossmatch test using the albumin-antiglobulin method, three episodes of DHTR occurred after surgery. The first hemolytic episode on day 7 after surgery was due to anti-Di(a) because of clinical and laboratory evidence which included jaundice, sudden increases in total bilirubin (T-Bil) and lactate dehydrogenase (LD) levels, and a decrease (2.2 g/dl) in hemoglobin (Hb) level. The second hemolytic episode on day 16 resulted from newly producted anti-Jk(b). The patient experienced fever, fatigue, nausea and anorexia, and laboratory data showed a second increase in T-Bil, a second decrease (3 g/dl) in Hb, and moderate elevations of blood urea nitrogen (BUN) and creatinine (CRE) levels. The third hemolytic episode on day 39 was due to anti-E. The patient complained of fever and fatigue and had a third unexplained drop (1.5 g/dl) in Hb despite no bleeding. This is the first reported case in which three episodes of DHTR occurred from different red cell antibodies.

Polymorphisms of RhD(Va) and a new RhD(Va)-like variant found in Japanese individuals

BACKGROUND AND OBJECTIVES

Red cell type RhD(Va) lacks epD1 and 5 and is encoded by hybrid RHD-CE(5)-D alleles. We analyzed RhD(Va) and RhD(Va)-like samples in Japanese blood donors.

MATERIALS AND METHODS

Ten RhD(Va) samples lacked epD1 and 5 and 3 RhD(Va)-like variants also lacked, epD2 and a part of 6/7. We identified the full-length nucleotide sequences of the complementary DNA (cDNA) synthesized from 4 samples: 3 of type D(Va) and the 4th a D(Va)-like variant.

RESULTS

Although their sequences differed from each other, all the substitutions were exclusively in exon 5. Three D(Va) samples had hybrid RHD-CE(5)-D alleles, but the D(Va)-like variant had a unique nucleotide substitution with a single amino acid change, E233K. Exon 5 of the genomic DNA from all 13 samples was analyzed by sequencing. No other sequences were identified.

CONCLUSION

All RhD(Va) and RhD(Va)-like variants had the substitution for E233. E233 seems to be a determinant of epD1 and 5. A new category of RhD variant, DYO, was identified.

Molecular cloning and characterization of decay-accelerating factor deficiency in Cromer blood group Inab phenotype

An additional decay-accelerating factor (DAF) mutation, designated as Inab phenotype in the Cromer blood group system, was recently identified in a 28-year-old Japanese woman (H.A.). The red blood cells of H.A., like those of other Inab phenotype individuals, were negative for Cromer system antigens, Cra, Tca, Dra, UMC, and IFC. The deficiency of DAF on the red blood cells of H.A. has been shown by immunoblotting with a murine monoclonal antibody to DAF. Molecular analysis has shown that H.A. is homozygous for a single nucleotide substitution, C1579-->A, at the position 24 bp upstream of the 3'-end of exon 2 of the DAF gene. This substitution causes the activation of a novel cryptic splice site and results in the production of mRNA with a 26 bp deletion. The deletion introduces a reading frame shift and creates a stop codon immediately downstream of the deletion. Translation of mRNA would be terminated at the first amino acid residue of the second short consensus repeat (SCR2) domain (exon 3) of DAF. The functional domains of DAF's complement regulatory activity and the carboxy-terminal signal domains for glycosylphosphatidylinositol (GPI) anchoring are predicted to be lacking in H.A. Thus, there would be no DAF present on the cell surface.

A new high-molecular-weight glycophorin C variant with a duplication of exon 2 in the glycophorin C gene

Glycophorin C (GPC) and glycophorin D (GPD) are closely related sialoglycoproteins in the human red blood cell (RBC) membrane. Both are thought to be encoded by the GPC gene (GYPC). We report here the new GPC variant, MAT, with a high-molecular-weight form of GPC and GPD. The murine monoclonal antibody to GPC (CBC-96), which had specificity for the N-terminal region of GPC, gave a stronger reactivity with the MAT RBCs than did normal RBCs in direct agglutination tests. Immunoblotting of the MAT RBC membranes with anti-GPC antibodies showed the apparent molecular weight of GPC.MAT and GPD.MAT was 5000 greater than that of their normal counterparts. cDNA was synthesized from total RNA obtained from three unrelated, heterozygous MAT blood donors and analysed by the polymerase chain reaction with primers that spanned sequences encoded by GYPC. Two fragments were generated: one was 510 bp, the other was 453 bp and corresponded to the normal GPC. Sequencing of the mutant 510-bp fragment showed an insert of 57 nucleotides that corresponds to the entire sequence of exon 2 in GYPC. These results show that MAT is the result of a duplication of exon 2 in GYPC, which probably encodes the two high-molecular weight forms GPC.MAT and GPD.MAT. The MAT mutation is found with a frequency of 0.02% in the Japanese population.

Family study of acute intermittent porphyria and hereditary coproporphyria in Niigata and Akita Prefectures, Japan

Simple screening tests, urinary porphobilinogen (PBG) for acute intermittent porphyria (AIP) and fecal coproporphyrin for hereditary coproporphyria (HCP), were performed in a family study of AIP and HCP. Urinary PBG was positive in 93 of 211 members of 10 AIP families, but was negative in 568 of 572 controls. Fecal coproporphyrin was positive in 54 of 108 members of 10 HCP families, but was negative in 188 controls. A dominant inheritance was assumed by a chi-square test and Weinberg segregation ratio. Worsening factors around puberty were suggested by the onset age and cumulative percentage of genetically loaded cases. Sex-related expression of symptoms was also inferred by a higher incidence of both porphyrias in females than in males. Fitness and penetrance of both porphyrias were good. An l-triiodothyronine loading test was the most useful for the detection of masked carriers of AIP. In conclusion, AIP and HCP in Japan show a dominant inheritance with sex-related metabolic and clinical manifestations.

Serological analysis of monoclonal anti-E and -e with Japanese E/e variant red cells

The agglutination patterns have been analyzed for the reaction between 24 monoclonal antibodies (MAB) with specificity for the Rh antigen E or e and red cells of E/e variant from Japanese blood donors. The MABs were tested for direct agglutination of papain treated cells at 20 degrees C. The reactions of a full titration series of each MAB with a E/e variant cell were compared to the reactions of that MAB with normal E + e + cells. Sixteen anti-E were divided into a minimum of 6 different agglutination patterns with 8 examples of E variant cells. Eight anti-e gave a minimum of 5 different agglutination patterns with 6 examples of e variant cells.

First case of hemolytic disease of the newborn due to anti-Ula antibodies

The first case of hemolytic disease of the newborn (HDN) due to anti-Ula antibodies is described. The infant had severe anemia with a positive direct antiglobulin test with anti-IgG that required blood transfusion. But jaundice was not severe enough for exchange transfusion or phototherapy.