title: A study of 45,X/46,XX mosaicism in Turner syndrome females: a novel primer pair for the (CAG)n repeat within the androgen receptor gene.
abstract: This paper describes the procedures developed for the determining of diparental/uniparental origin of X chromosomes in mosaic Turner females (karyotype 45,X/46,XX), and accounts for results of the analysis of chromosomal material from 20 girls with Turner syndrome. An (CAG)n repeat within the androgen receptor (AR) gene was selected as a genetic marker. A novel primer pair for amplification of the (CAG)12-30 repeat was designed. These primers gave an amplification product of 338 bp in length and were following (5'-->3'): agttagggctgggaagggtc and cggctgtgaaggttgctgt. Nineteen of the subjects were heterozygous for the selected marker. In 4 cases there were distinct signals from three alleles. The only Turner female in the study who had been previously ascribed a non-mosaic 45,X karyotype by using cytogenetic techniques, proved to be a cryptic mosaic, displaying two alleles of the genetic marker in the more sensitive molecular assay. These results suggest that in most cases 45,X/46,XX mosaicism in Turner females arises through loss of one of the X chromosomes in some cell lines in originally 46,XX conceptuses, rather than through mitotic non-disjunction during early embryogenesis in originally 45,X conceptuses. A high sensitivity of the modified assay based on PCR-amplification of the (CAG)n repeat within AR gene proves its usefulness as a tool for studying mosaicism in Turner syndrome.
authors.affiliation: Centre of Reproductive Medicine, Sahlgrenska University Hospital, Göteborg, Sweden. julia.leonova@anatcell.gu.se
authors.forename: J
authors.initials: J
authors.lastname: Leonova
authors.forename: C
authors.initials: C
authors.lastname: Hanson
mesh_terms: D002648:Child; D004247:DNA / Q000097:blood; D005260:Female; D006801:Humans; D007621:Karyotyping; D009030:Mosaicism / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011944:Receptors, Androgen / Q000235:genetics*; D018911:Trinucleotide Repeats; D014424:Turner Syndrome / Q000235:genetics*; D014960:X Chromosome
chemical_list: D011944:Receptors, Androgen; D004247:DNA