title: Extended structural variation of a pentanucleotide repeat in the GSTP1 gene: characterisation in a normal population and in thyroid and gastric tumours.
abstract: The promoter region of the human GSTP1 gene contains a polymorphic short tandem repeat (STR) locus consisting of pentanucleotide repeat units (ATAAA). In this work we report the existence of a total of 26 alleles in a Caucasian population. While differences in size (ranging from one to five base pairs) were responsible for the major variation, in five size-defined classes, two alternative sequences were found. Automatic fragment sizing and sequencing analysis revealed that this polymorphism is of a highly complex nature in contrast with previous reports. A genetic population study was carried out on a random sample from Portugal showing no deviation from Hardy-Weinberg equilibrium. Somatic instability studies were also performed on gastric and thyroid tumours using this STR: no instability was detected in thyroid tumour tissues when compared with their normal counterpart but in gastric tumour tissues microsatellite instability (MSI) was detected in 9.6% of the cases and loss of heterozygosity (LOH) also in 9.6% of the cases studied. The results obtained with GSTP1 in gastric cancer were compared with previously reported data on MSI using BAT-26 and several dinucleotide repeat markers.
authors.affiliation: Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Portugal. calves@ipatimup.pt
authors.forename: C
authors.initials: C
authors.lastname: Alves
authors.forename: F
authors.initials: F
authors.lastname: Silva
authors.forename: L
authors.initials: L
authors.lastname: Gusmão
authors.forename: R
authors.initials: R
authors.lastname: Seruca
authors.forename: P
authors.initials: P
authors.lastname: Soares
authors.forename: R M
authors.initials: RM
authors.lastname: Reis
authors.forename: A
authors.initials: A
authors.lastname: Amorim
mesh_terms: D000483:Alleles; D004252:DNA Mutational Analysis; D017931:DNA Primers / Q000737:chemistry; D005787:Gene Frequency; D005819:Genetic Markers; D005838:Genotype; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D019656:Loss of Heterozygosity; D018598:Minisatellite Repeats; D009154:Mutation; D009841:Oligonucleotides / Q000737:chemistry*; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013274:Stomach Neoplasms / Q000201:enzymology*; D013964:Thyroid Neoplasms / Q000201:enzymology*
chemical_list: D017931:DNA Primers; D005819:Genetic Markers; D007527:Isoenzymes; D009841:Oligonucleotides; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase