Analysis of sex chromosome aneuploidy in 41 patients with Turner syndrome: a study of 'hidden' mosaicism.
We performed a genetic study of sex chromosome mosaicism in 41 Turner syndrome patients. The investigation was carried out in four phases: cytogenetics (G-banding), FISH, PCR for SRY in all 41 cases, and sequencing of the SRY gene in the 2 patients with the Y chromosome. The application of classical alpha-satellite probes (CEP-X and CEP-Y), painting probes (WCP-X and WCP-Y) and also XIST, DXZ4 and two subchromosomal painting libraries (SCPL 116 and SCPL102) covering the short and the long arm of the X chromosome, respectively, allowed us to find new mosaic cell lines (mosaicism) in 37 out of 41 patients; only 4 patients were defined as 45,X non-mosaic. The most frequent hidden mosaic was 45,X/46,XX in 32% of the cases; the presence of isochromosomes comprised 25% and markers 5%. The patients who had been previously diagnosed as mosaics displayed a higher complexity in their karyotypes due to the presence of new cell lines. The Y chromosome and the SRY gene were present in blood and ovarian tissue in 2 patients with karyotypes 45,X/46,XY and 45,X/46,X,idic(Ynf). In both patients, the sequencing of the SRY gene confirmed a nucleotide sequence identical to that of a control male. Our results support the hypothesis of 'the necessity of mosaicism for survival', and thus, a mitotic origin for this syndrome.
Fernández-García
R
R
Department of Psychobiology, University of A Coruña, Spain.
García-Doval
S
S
Costoya
S
S
Pásaro
E
E
D000782:Aneuploidy; D002871:Chromosome Banding; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D009030:Mosaicism / Q000235:genetics*; D009687:Nuclear Proteins; D016366:Open Reading Frames / Q000235:genetics; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D017422:Sequence Analysis, DNA; D012730:Sex Chromosomes / Q000235:genetics*; D051876:Sex-Determining Region Y Protein; D014157:Transcription Factors; D014424:Turner Syndrome / Q000235:genetics*
D015342:DNA Probes; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C497745:SRY protein, human; D051876:Sex-Determining Region Y Protein; D014157:Transcription Factors