A novel A allele with 664G>A mutation identified in a family with the Am phenotype

BACKGROUND: The Am phenotype has been characterized as a weak expression of the A antigen on red blood cells but the presence of a normal quantity of the A antigen in saliva. This study describes a molecular genetic analysis of members of an Am family. STUDY DESIGN AND METHODS: The eight exon regions of the ABO genes of the Am proposita were amplified by polymerase chain reaction and cloned, and their sequences were analyzed. The alpha-1,3-N-acetylgalactosaminyltransferase (A-transferase) activities of the Am serum and the expressed Am transferase were analyzed. RESULTS: An A gene with a 664G>A mutation, which predicts an amino acid alteration of Val222Met, was identified in the Am proposita. This Am664A allele was demonstrated in other three family members with the Am phenotype. The A-transferase activity was virtually undetectable in the Am sera, and the expressed Am transferase showed weak A-transferase activity, when compared with the expressed A1 transferase, in assays that use acceptor substrates mimicking the Type 2 H structure and Type 1 H structure. CONCLUSION: A novel A allele with 664G>A mutation was demonstrated in a pedigree with the Am phenotype. The mechanism leading to the formation of the Am phenotype still awaits elucidation.     

A novel FUT1 allele was identified in a Chinese individual with para-Bombay phenotype

Background: The para‐Bombay phenotype is characterised by H‐deficient or H partially deficient red blood cells (RBCs) in individuals who secrete ABH antigens in their saliva. Samples from an individual whose RBCs had an apparent para‐Bombay phenotype and his family members were investigated and a novel FUT1 allele was identified. Materials and Methods: RBCs' phenotype was characterised by standard serologic technique. Genomic DNA was sequenced with primers that amplified the coding sequence of FUT1 and FUT2, respectively. Routine ABO genotyping analysis was performed. Haplotypes of FUT1 were identified by TOPO cloning sequencing. Recombination expression vectors of FUT1 mutation alleles were constructed and transfected into COS‐7 cells. The pα‐(1,2)‐fucosyltransferase activity of expression protein was determined. Results: B101/O02 genotype of the proband was correlated with ABH substances in saliva. The proband carried a new FUT1 allele which showed 35C/T, 235G/C and 682A/G heterozygote by directly DNA sequencing. Two haplotypes, 235C and 35T+682G, were identified by TOPO cloning sequencing and COS‐7 cells transfected with five recombination vectors including wild‐type, 35T, 235C, 682G and 35T+682G alleles were established respectively. The α‐(1,2)‐fucosyltransferase activities of cell lysates which had transfected with 35T, 235C, 682G and 35T+682G recombination vectors showed 79·45, 16·23, 80·32 and 24·59%, respectively, compared with that of the wild‐type FUT1‐transfected cell lysates. Conclusion: A novel FUT1 allele 235C was identified, which greatly diminished the activity of α‐(1,2)‐fucosyltransferase.     

A novel RHD allele caused by c.739 G> C mutation was identified in a Chinese individual

The blood sample of a pregnant Chinese woman of the north Han population was confirmed as D variation by serologic method, and subsequent detection of RHD Exons 1 through 10 by the polymerase chain reaction–sequence-specific primer test showed that all exons were present. To further clarify the molecular mechanism of this sample, we sequenced the RHD Exons 1 through 10 and found that it was a novel allele caused by c.739 G> C in Exon 5.     

A novel nonsense mutation in RHAG gene responsible for Rhnull phenotype in a Chinese individual

Background

Rh_null is a rare autosomal recessive phenotype, which is characterized by the lack of Rh antigen expression on the red blood cells (RBCs). Rh_null of the regulator type is caused by RHAG mutation. In this study, a novel nonsense mutation in RHAG gene was identified in a Chinese Rh_null individual.

B亚型中Bx新等位基因的鉴定

目的对ABO血型中B亚型分子遗传背景的研究,发现并鉴定ABO新等位基因。方法对5份血型血清学鉴定为B亚型的样本,采用PCR-SSP、ABO基因第6及第7外显子直接测序方法进行基因定型;并对目的B亚型样本进行RT-PCR、巢式PCR扩增、测序,分析其cDNA结构的差异。结果5份血清学为B亚型的样本中,血清学鉴定为Bx的个体发现了一个新的B等位基因。该等位基因与B101等位基因相比,差异仅在于第7外显子的B基因序列中nt721位C>T突变。其余4份B亚型样本的ABO基因第6、7外显子都未发现新的点突变。结论首次在中国汉族人中发现一个721C>T新变异的B等位基因,该等位基因nt721位由C转变为T,241位氨基酸由精氨酸转变为色氨酸,可导致糖基转移酶活性的降低,表明ABO基因的第241位氨基酸对决定糖基转移酶活性是至关重要的。     

A family study of the Chinese Rhnull individual of the regulator type: a novel single missense mutation identified in RHAG gene

BACKGROUND: Rh_null is a rare autosomal recessive disorder, and Rh_null of the regulator type may result from mutation of the RHAG gene, which encodes RhAG glycoprotein and modulates Rh antigen expression. This study described the molecular genetic analysis of a Chinese Rh_null family and identified a novel mutation in the RHAG gene. STUDY DESIGN AND METHODS: RBCs from the Rh_null family members were analyzed for Rh phenotype by standard methods. DNA sequences of all 10 exons of RHAG gene were analyzed using genomic DNA by polymerase chain reaction and direct DNA sequencing. RESULTS: Genomic DNA analyses showed that a 672C>A mutation in Exon 5 of the RHAG gene was present at the homozygous state in DH and at the heterozygous state in the other members of the Rh_null family. The 672C>A missense mutation converted serine into arginine at Position 224 in the Transmembrane Segment 7 of RhAG glycoprotein. CONCLUSION: These findings provide evidence that the 672C>A missense mutation in the RHAG gene could result in Rh_null of the regulator type, and the single‐amino‐acid change (Ser to Arg) might be critical for assembly of the Rh antigen complex within the membrane.