Phenotypic and genotypic variability in monozygotic triplets with Turner syndrome.
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.
Lespinasse
J
J
Laboratoire de Cytogénétique, Centre hospitalier de Chambéry, France.
Gicquel
C
C
Robert
M
M
Le Bouc
Y
Y
D000293:Adolescent; D000328:Adult; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007621:Karyotyping; D009030:Mosaicism; D010641:Phenotype; D014310:Triplets / Q000235:genetics*; D014424:Turner Syndrome / Q000235:genetics*; D014960:X Chromosome