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Analysis of sex chromosome aneuploidy in 41 patients with Turner syndrome: a study of ‘hidden’ mosaicism
Author(s) -
FernándezGarcía R,
GarcíaDoval S,
Costoya S,
Pásaro E
Publication year - 2000
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1034/j.1399-0004.2000.580307.x
Subject(s) - testis determining factor , karyotype , biology , y chromosome , turner syndrome , x chromosome , genetics , chromosome , xist , cytogenetics , microbiology and biotechnology , gene , x inactivation , endocrinology
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 (SCPL116 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.