Phenotypic and genotypic variability in monozygotic triplets with Turner syndrome |
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Authors: | J. Lespinasse C. Gicquel M. Robert Y. Le Bouc |
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Affiliation: | Laboratoire de Cytogénétique, Centre hospitalier de Chambéry, 73000 Chambéry;Laboratoire d'Exploration Fonctionnelles Endocriniennes et Unitéde Biologie Moléculaire, H pital Trousseau. 75012 Paris;Departement d'Endocrinologie, Centre hospitalier de Chambéry, 73000 Chambery, France |
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Abstract: | Turner syndrome (TS) is a common disorder (1/2500 and 1/5000 female births) which is diagnosed at birth in approximately 20% of patients and during childhood (usually due to growth retardation) or later, (due to lack of pubertal development) for the remaining patients. Here we present a cytogenetic and molecular analysis of three monozygotic sisters. The diagnosis of TS was done for one of them (patient 1) who presented with a typical Turner phenotype. A first karyotype was established as normal and a second karyotype (carried out on 200 cells) revealed a 45,X/46,XX mosaicism with 6% of cells with a 45,X karyotype. Lymphocyte karyotype analysis showed the same mosaicism pattern for the two other sisters, one of them exhibiting only a mild (patient 2) and the other no clinical features of Turner syndrome (patient 3). Karyotype analysis was this time conducted on fibroblasts and showed that the 45,X/46,XX mosaicism pattern correlated with the clinical phenotype with 99, 43 and 3% of 45,X cells in patients 1, 2, and 3, respectively. These data suggest that different tissues other than lymphocytes should be subjected to a karyotype analysis when the observed genotype does not correlate with the clinical phenotype. |
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Keywords: | lymphocyte karyotype monozygotic Turner syndrome |
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