Study on a novel mutation of B glycosyltransferase gene related with an ABx variant / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the molecular basis of an individual featuring an ABx variant of ABO blood group system.</p><p><b>METHODS</b>Serological assays were used to characterize the erythrocyte phenotypes and salivary ABH secretors. All of the seven exons and flanking introns of ABO glycosyltransferase gene were amplified with polymerase chain reaction (PCR). And the products were sequenced bidirectionally following enzyme digestion. Exons 6 and 7 were also subcloned and analyzed for haplotypes of the ABO gene.</p><p><b>RESULTS</b>Erythrocytes of the proband have expressed a strong A antigen and a weak B antigen, which was identified as a rare ABx variant in addition with other serological features. Nine heterozygous sites in exon 6 (297A/G) and exon 7 (467C/T, 526C/G, 657C/T, 703G/A, 796C/A, 803G/C, 808T/A, 930G/A) of the coding region of the ABO gene were identified. Based on haplotype analysis, one allele was determined as common A102, whilst another was consistent with B101 except for an 808T>A mutation which has resulted in replacement of phenylalanine with isoleucine at position 270 of glycosyltransferase B.</p><p><b>CONCLUSION</b>The 808T>A mutation of the glycosyltransferase B gene may decrease the enzymatic activity and result in the Bx variant.</p>

Analysis of allele frequencies of HLA-DRB1*12:01:01G and HLA-DRB1*14:01:01G groups / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To discriminate and analyze the relative frequencies of alleles in HLA-DRB1*12:01:01G(HLA-DRB1*12:01:01/12:06/12:10/12:17) and HLA-DRB1*14:01:01G (DRB1*14:01:01/14:54) groups and assess their associations with HLA-DRB3 and HLA-DQB1 loci.</p><p><b>METHODS</b>A total of 115 DNA samples previously typed as HLA-DRB1*12:01:01G and 108 samples from HLA-DRB1*14:01:01G were selected. DNA sequences for exons 1 to 3 of the HLA-DRB1 locus were analyzed for HLA-DRB1*12:01:01G, and exons 2 to 3 were analyzed for HLA-DRB1*14:01:01G by polymerase chain reaction sequence-based typing (PCR-SBT). Genotyping of HLA-DRB3 and HLA-DQB1 were achieved by PCR-SBT.</p><p><b>RESULTS</b>Among 115 samples previously typed as HLA-DRB1*12:01:01G, 101 (87.8%) were confirmed as HLA-DRB1*12:01:01 and 14 (12.2%) were HLA-DRB1*12:10, but HLA-DRB1*12:06 and HLA-DRB1*12:17 alleles were not identified. For 108 samples previously typed as HLA-DRB1*14:01:01G, all were typed as HLA-DRB1*14:54. HLA-DRB1*12:01:01 was linked with HLA-DRB3*01:01:02 and HLA-DQB1*03:01, while HLA-DRB1*12:10 was strongly linked with HLA-DRB3*02:02:01 and HLA-DQB1*03:01. HLA-DRB1*14:54 was strongly linked with HLA-DRB3*02:02:01 and two different HLA-DQB1*05:02, *05:03 alleles.</p><p><b>CONCLUSION</b>HLA-DRB1*12:01:01 was more prevalent than HLA-DRB1*12:10 in the HLA-DRB1*12:01:01G group, and HLA-DRB1*14:54 was the dominant allele for HLA-DRB1*14:01:01G.</p>

Molecular mechanism of an individual with weaken B phenotype in ABO blood group / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To elucidate the serological characteristics and molecular mechanism of a blood donor with weaken B antigen.</p><p><b>METHODS</b>The ABO blood group antigens on red blood cells were identified by monoclonal antibodies, the ABO antibodies in serum were detected by standard A, B, O cells and the activity of the B glycosyltransferase was analyzed. The full-length sequence and 5'-untranslated region (5'-UTR) sequence of ABO gene were amplified by polymerase chain reaction (PCR) respectively and direct sequencing. The alternative splicing isoforms of ABO cDNA were obtained by reverse transcription-PCR(RT-PCR) and analyzed with cloning and sequencing techniques. The level of methylation of the CpG island in ABO gene promoter was analyzed by bisulfite sequencing method.</p><p><b>RESULTS</b>The serological characteristic of the donor showed that the B antigen was decreased obviously without anti-B antibodies in serum and the B glycosyltransferase activity was decreased as well. The genotype of the donor was B101/O01 without any other mutations in the full-length coding sequences and splice receptor sites. The nucleotide characteristics of the 5'-UTR was consistent with B101/O01 and no any abnormity was identified in the promoter, enhancer and the negative regulatory sequence regions. The integrative cDNA transcript of ABO gene was obtained and no new splicing isoform was found. Compared with the normal B phenotype, a number of methylated CpG sites were found near the promoter of ABO gene in this sample.</p><p><b>CONCLUSION</b>The methylation in the CpG island of ABO gene promoter region may cause weak expression of the B antigen.</p>

Recombination between human leukocyte antigen -A and -C loci within two Chinese Han families / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the recombination events between human leukocyte antigen (HLA) loci within two families.</p><p><b>METHODS</b>Identification of HLA-A, -C, -B, -DRB1 and -DQB1 loci was firstly carried out using polymerase chain reaction-sequence specific oligonucleotide. Then HLA high resolution typing was performed using polymerase chain reaction sequencing-based typing. The recombination between HLA loci was identified by family genetic analysis. The parentage possibility was analyzed by short tandom repeat technique.</p><p><b>RESULTS</b>Recombination between the HLA-A and C loci was identified within two families. One individual inherited a paternal haplotype that was the result of a recombination event between the father's HLA-A and -C loci on his chromosomes. The other individual inherited a maternal haplotype that was the result of a recombination event between the mother's HLA-A and -C loci. The high parentage possibilities were obtained in the family members.</p><p><b>CONCLUSION</b>The recombination events of HLA-A and -C have been found in two Chinese families, which may help further study on the mechanism of HLA recombination.</p>

Study on the expression stability of mutant alpha-1,2 fucosyltransferase gene 293C to T and 658C to T in eukaryotic cells / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To establish the eukaryotic cell expression system for the alpha-1,2 fucosyltransferase gene FUT1 293C to T and 658C to T mutations and explore the mechanism of FUT1 mutations resulting in the reduced expression of H antigen.</p><p><b>METHODS</b>Genomic DNAs were extracted from individuals with para-Bombay phenotype and full coding region of FUT1 was amplified. The amplification fragments were ligated with pcDNA3.1 plasmid to construct the recombinant expression vectors. The recombinant plasmids were transfected into the COS-7 cells using lipofectamine transfection reagent and stable expression screening was performed. FUT1 mRNA expression was determined by real-time quantitative PCR. The activity of enzyme was measured by high performance liquid chromatography. Expressed protein was identified by SDS-PAGE and Western blotting.</p><p><b>RESULTS</b>pcDNA3.1-FUT1 wildtype, pcDNA3.1-FUT1 293C to T and pcDNA3.1-FUT1 658C to T recombinant vectors were constructed, respectively. COS-7 cells with stable expression of FUT1 were obtained through recombinant plasmid transfection and screening with G418. The FUT1 mRNA level of transfected cells with 293C to T and 658C to T recombinant vectors reached 97.10% and 104.74% of the wildtype FUT1 transfected cell. A specific protein band with about 46 000 was confirmed in the transfected cell lysates by SDS-PAGE electrophoresis and Western blotting with 6×His Tag antibody. The wildtype FUT1 transfected cell lysates can catalyze the enzymatic reaction, while the enzyme activity of cell lysates from 293C to T and 658C to T were abolished.</p><p><b>CONCLUSION</b>The results suggested that the 293C to T and 658C to T mutations of FUT1 gene did not affect the RNA and protein expression levels, but the enzyme activity of cells with FUT1 mutations was significantly decreased which resulted in the reduced expressin of H antigen.</p>

Identification of an ABx09 phenotype of ABO subtype / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the molecular basis for an individual with ABx09 phenotype of ABO subtype.</p><p><b>METHODS</b>The ABO group antigens on red blood cells of the proband were identified by monoclonal antibodies, and the ABO antibody in serum was detected by standard A, B, O cells. The exons 1 to 7 of ABO gene were amplified by polymerase chain reaction (PCR) respectively and the PCR products were sequenced directly. The amplified products for exons 5 to 7 were also cloned by TOPO TA cloning sequencing kit to split the two alleles apart, selected colonies were sequenced bidirectionally for exons 5 to 7 of the ABO gene. The samples of the proband's parents were collected, then serological test of the blood group and sequence analysis for exons 6 and 7 of ABO gene were preformed.</p><p><b>RESULTS</b>Both A and B antigens were detected on red blood cells of the proband and there was anti-B antibody in the serum. There was no G deletion at position 261, while 297AG in exon 6, 467CT, 526CG, 657CT, 703GA, 796CA, 803GC, 889GA and 930GA heterozygote in exon 7 were detected by direct DNA sequencing, which can be assigned for A102Bx09 genotype. After cloning and sequencing, two alleles A102 and Bx09 were obtained. The sequence of Bx09 had one nucleotide changes (G to A) at position 889 compared with that of B101, which resulted in an amino acid change of Glu to Lys at 297 position. The Bx09 in the proband was inherited from her mother by family investigation.</p><p><b>CONCLUSION</b>G to A at nt889 of alpha-1,3 galactosyltransferasegene can result in Bx09 phenotype, with the presence of anti-B antibody in serum.</p>

Study on polymorphism of membrane glycoprotein genes related to human platelet alloantigens / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the polymorphisms of platelet membrane glycoprotein genes related to human platelet alloantigen (HPA)-1 to 17w.</p><p><b>METHODS</b>The DNA segments of platelet membrane glycoprotein genes related to HPA-1 to 17w were amplified using author's designed primers. The amplification products were purified and directly sequenced to identify the HPA genotype and glycoprotein gene polymorphisms.</p><p><b>RESULTS</b>Thirteen new single nucleotide polymorphisms (SNPs) and a micro-satellite sequence were found in the glycoprotein genes from the 112 random samples, in which two SNPs (1333G/A and 1960G/A) in ITGB3 gene result in two amino acid change (V419M and E628K) on glycoprotein GPIIIa.</p><p><b>CONCLUSION</b>New variants in platelet membrane glycoprotein genes were identified, which may lead to structure change of platelet membrane glycoprotein and affect the accuracy of partial HPA genotyping method.</p>

Cloning and sequence analysis of 5'untranslated region of human ABO gene / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To clone and investigate the polymorphism of the 5'-untranslated region (5'-UTR) of the human ABO gene, in order to provide the basis for exploring the transcriptional regulation of the human ABO histo-blood group genes.</p><p><b>METHODS</b>ABO phenotypes of 30 unrelated healthy blood donors were determined by serological technique, their genotypes were analyzed by sequencing the exons 6 and 7 of the ABO gene. Nearly 5 kb of the 5'-UTR of ABO gene was obtained by PCR amplification and sequencing was performed bidirectionally. Haplotypes of samples with heterozygous sites in the 5'-UTR of ABO gene were separated and analyzed after cloning.</p><p><b>RESULTS</b>Twenty polymorphic sites were identified in these samples where ABO genotypes were consistent with serological phenotypes. It included sixteen nucleotide sequence variations, one 8 bp deletion, one 6 bp deletion/insertion, one 36 bp insertion and one 43 bp repeats. Among them, 11 were novel polymorphic sites. Seven different haplotypes of 5'-UTR of ABO gene were defined to the cis/trans linkage of those mutations.</p><p><b>CONCLUSION</b>There were polymorphisms in the 5'-UTR of ABO gene and the nucleotide sequences near the proximal promoter were conservative.</p>

Identification of a novel allele HLA-B*15:129 by polymerase chain reaction with allele group-specific primers / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the sequence of the exons 2-4 of human leukocyte antigen (HLA) novel allele HLA-B*15:129.</p><p><b>METHODS</b>DNA of the proband was extracted from whole blood by commercial DNA extraction kit. The amplification for HLA-B exons 2-4 was performed separately by polymerase chain reaction (PCR) with allele group specific primers. The PCR products were digested with enzymes and then directly sequenced for exons 2-4 of HLA-B locus in both directions.</p><p><b>RESULTS</b>Sequencing results showed the HLA-B alleles of the proband included B*07:02 and a novel allele. The sequence of the novel allele has been submitted to GenBank (accession no. EF473219) and the allele has been officially named B*15:129 by the WHO Nomenclature Committee. Comparing with the HLA-B*15:01:01:01, the sequence of exons 2-4 of HLA-B*15:129 showed three nucleotide difference in exon 3 at positions 362 and 363 from GG to AT and positions 369 from C to T, which resulted in an amino acid change from Arg to Asn at codon 97.</p><p><b>CONCLUSION</b>A novel HLA-B allele was identified and has been officially named B15:129 by the WHO Nomenclature Committee.</p>

Analysis of alpha-1,2-fucosyltransferase gene mutations in a Chinese family with para-Bombay phenotype / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the molecular genetic basis of para-Bombay phenotype in a Chinese family.</p><p><b>METHODS</b>ABO and H phenotypes of the proband and his pedigree were characterized by serological techniques. The exons 6 and 7 of the ABO gene and full coding region of alpha-1,2-fucosyltransferase (FUT1) gene of the pedigree were analyzed by polymerase chain reaction and direct sequencing of the amplified fragments. The haplotypes of compound heterozygote of the FUT1 gene were also analyzed by cloning sequencing.</p><p><b>RESULTS</b>Three para-Bombay phenotypes were identified in nine family members by serological technology. Three heterozygous variants (35C/T, 235G/C and 682A/G) were found in FUT1 gene of the proband, and the hapotype of FUT1 gene was h(235C)/h(35T+628G)according to the cloning sequencing. The alleles h(235C)and h(35T+628G) caused G79R, A12V and M228V amino acid substitutions in alpha-1,2-fucosyltransferase, respectively.</p><p><b>CONCLUSION</b>A novel 235G>C mutation of FUT1 gene which was associated with para-Bombay phenotype was found in the Chinese pedigree.</p>

Establishment of allele specific primer polymerase chain reaction sequence-based typing and investigation of the polymorphism in exon 3 of HLA-DRB1 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To establish the allele specific primer polymerase chain reaction sequence-based typing (PCR-SBT) and investigate the polymorphism of exon 3 of human leukocyte antigen( HLA)-DRB1.</p><p><b>METHODS</b>The fragment containing exons 2 and 3 of HLA-DRB1 gene was amplified by group specific primers. The amplified products were digested by restriction enzymes and directly sequenced in both directions. The genotype was assigned by using Assign 3.5 SBT software.</p><p><b>RESULTS</b>The exon 3 sequences of HLA-DRB1*08:09 and HLA-DRB1*12:02:01 were identified for the first time. There were 27 polymorphic sites in exon 3 among the twenty-five HLA-DRB1 alleles, which was 9.56% of all nucleotides of exon 3. The method could discriminate the HLA-DRB1*14:01:01/14:54 ambiguous samples, and the HLA-DRB1*14:01:01 was identified in the Chinese population.</p><p><b>CONCLUSION</b>The PCR-SBT method for exon 3 of HLA-DRB1 from the present study was reliable and there were polymorphisms in exon 3 of HLA-DRB1.</p>

A novel M142T mutation in the B glycosyltransferase gene associated with B3 variant in Chinese / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the molecular genetic basis of the B3 variant of ABO blood group system with mixed-field hemagglutination in Chinese.</p><p><b>METHODS</b>Serological techniques were performed to characterize the erythrocyte phenotype of two discrepant samples. A sequential agglutination method and 13 short tandem repeat (STR) loci were tested to exclude the possibility of exogenous or endogenous DNA chimera. Mutations in exons 6 and 7, including partial intron of the ABO gene, were screened by polymerase chain reaction and DNA sequencing. Haplotypes of the two individuals were also analyzed by sequencing.</p><p><b>RESULTS</b>A mixed-field hemagglutination of RBCs with anti-B and anti-AB antibodies was detected in the two unrelated individuals. Exogenous ABO-incompatible RBC transfusion and endogenous genetic chimera were excluded by sequential agglutination method and STR. The ABO phenotypes of the two individuals were classified as A1B3 according to the ABO subgroup definition. The sequence region from intron 5 to 3'-UTR of the B allele was identical to that of ABO*B101 allele, except for a T to C substitution at nucleotide position 425 in exon 7. This substitution resulted in an amino acid change of M142T in the B glycosyltransferase.</p><p><b>CONCLUSION</b>A novel B allele with 425T>C substitution resulting in B3 subgroup was identified in two Chinese individuals.</p>