Searching chromosome mosaicisms in 45,X Turner syndrome: how relevant is it?

Abstract

Objective: To investigate the presence of chromosome mosaicism, especially for the presence of Y derived material in 45,X women with Turner syndrome (TS). Materials and methods: FISH and PCR were performed for the presence of chromosome mosaicism and Y-derived-material and genetic findings were correlated to clinical data. Results: Thirty-one participants were enrolled: 18 (58%) had chromosome mosaicisms (FISH), Y-derived material was found in 2. Yet, SRY primer was found with PCR in only one of them and DYZ3 was not found. The most frequent clinical findings were short or webbed neck (81,82%), high-arched palate (78%), breast hypertelorism, e cubitus valgus and genu valgus (57.6%, both), short fourth metacarpals (46.9%), epicanthic folds (43.8%), shield chest (43.8%), lymphedema (37.5%), and low set ears (34.4%). Both patients with Y-derived-material had primary amenorrhea, dyslipidemia and reached the height of 150 cm despite not treated with recombinant growth hormone (GHr). One of them showed 26% of leukocytes with Y-derived material and few clinical findings. Conclusions: FISH techniques proved efficient in detecting chromosome mosaicisms and Y-derived material and searching in different tissues such as mouth cells is critical due to the possibility of tissue-specific mosaicism. Phenotypical variance in TS may be a signal of chromosome mosaicisms, especially with the presence of Y-derived material.

Karyotyping of Lymphocytes and Epithelial Cells of Distinct Embryonic Origin Does Not Help to Predict the Turner Syndrome Features

“…We expected that a substantial of X monosomy cases would be reclassified to the "low-frequency" 45,X/46,XX mosaic form by using the FISH method. Our expectation was driven by the findings of previous studies that investigated the role of FISH form buccal smear and proposed that tissue-specific karyotyping may explain the discrepancies between karyotypes and phenotypes of individuals with TS [17,18]. However, the FISH of the cells originating from the three distinct germ layers verified X monosomy in the majority of our patients.…”

“…However, this was not confirmed by another recent analysis [15]. In addition, studies that explored the tissue-specific mosaicism revealed substantial karyotype differences and indicated that the use of FISH analyses of buccal smears could potentially help to clarify the phenotypic variability in TS [16-18]. Considering the mechanism by which somatic mosaicism emerges [19], it cannot also be excluded that the phenotype of individuals with TS depends on whether the loss of the X chromosome occurred before or after the formation of all three germ layers.…”