title: The repeat expansion detection method in the analysis of diseases with CAG/CTG repeat expansion: usefulness and limitations.
abstract: The repeat expansion detection (RED) method was described to detect expansions of trinucleotide repeats of unknown chromosomal location. We have improved the RED method by the use of 8-mer oligonucleotides and assessed its usefulness in 30 samples from patients with spinocerebellar ataxia type 1 (SCA1), Huntington's disease (HD), and Machado Joseph's disease (MJD), for which the number of CAG/CTG repeats was determined by sequencing. There was a good correlation between the number of repeats detected by sequencing and those identified by RED. However, in 17% of samples, the RED gave additional fragments for ligation products of different size than the CAG/CTG repeat expansion detected in the sample by sequencing. The same was observed in a group of control subjects (n = 78) without known clinical abnormalities in which products of more than 40 repeats were detected in 27% of them, indicating that CAG/CTG repeat expansions are common in the general population. Wether this corresponds to unidentified loci with expansions deserves further investigation.
authors.affiliation: Departament de Formació i Investigació, Hospital Psiquiàtric Universitari Institut Pere Mata, Reus, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Martorell
authors.forename: M A
authors.initials: MA
authors.lastname: Pujana
authors.forename: V
authors.initials: V
authors.lastname: Volpini
authors.forename: A
authors.initials: A
authors.lastname: Sanchez
authors.forename: J
authors.initials: J
authors.lastname: Joven
authors.forename: E
authors.initials: E
authors.lastname: Vilella
authors.forename: X
authors.initials: X
authors.lastname: Estivill
mesh_terms: D004247:DNA / Q000032:analysis; D004252:DNA Mutational Analysis / Q000379:methods*; D006801:Humans; D006816:Huntington Disease / Q000235:genetics*; D017827:Machado-Joseph Disease / Q000235:genetics*; D009841:Oligonucleotides; D011110:Polymorphism, Genetic; D013132:Spinocerebellar Degenerations / Q000235:genetics*; D018911:Trinucleotide Repeats / Q000235:genetics*
chemical_list: D009841:Oligonucleotides; D004247:DNA