Molecular Basis of the A2B in Taiwan
| Autor: | Chin-Wen Lin, 林晴雯 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 The ABO locus has three main allelic forms: A allele, B allele, and O allele. It is located on chromosome 9 at 9q34.1-q34.2 and contains 7 exons that span more than 18 kb of genomic DNA. Exon 7 is the largest and contains most of the coding sequence. Exon 6 contains the deletion that is found in most O alleles and results in a loss of enzymatic activity. The A and B alleles differ from each other by seven nucleotide substitutions, which result in A and B transferases that differ by four amino acids (Arg176Gly, Gly235Ser, Leu266Met, Gly268Ala). The O allele differs from the A allele by deletion of guanine at position 261. The deletion causes a frameshift and results the lacking of enzymatic activity. Molecular genotyping of the ABO alleles has been widely used in ABO subgroups analysis and solved the rare ABO blood grouping discrepancies. One hundred and twenty-seven A2B donors were found from the 8448 AB blood donors collected from two blood centers in 2004 in Taiwan. Sixty-one A2B donors were analyzed by means of molecular methods to investigate the alleles resulting in the A2B phenotype distribution in Taiwan. The A2B phenotype was identified by serological test. The polymerase chain reaction-restriction fragment length polymorphism method was used to screen ABO alleles at nucleotide (nt) 261 and 703 based on the nt differences of the ABO alleles. The subgroups of the A2 allele were determined by the PCR-RFLP method. The discrepancies between the A2B phenotype and genotype of the A2B were then studied by subcloning and nucleotide sequence analyses. Fifty-five of 61 donors (90%) are A205 and B allele; two are A201 and B allele. Four cases were heterozygotes of cis-AB allele and O/B alleles. Two were cis-AB04 and O allele, one was cis-AB01 and O allele, and the other was cis-AB02 and B allele. Most A2B genotypes belong to A205 and B allele in Taiwan. The A205, A201, and cis-AB02 alleles are being reported for the first time in Taiwan. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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