Effect of chromosome constitution variations on the expression of Turner phenotype.

Turner syndrome (TS) is a chronic disease related to haploinsufficiency of genes that are normally expressed in both X chromosomes in patients with female phenotype that is associated with a wide range of somatic malformations. We made detailed cytogenetic and clinical analysis of 65 patients with TS from the region of Recife, Brazil, to determine the effects of different chromosome constitutions on expression of the TS phenotype. Overall, patients with X-monosomy exhibited a tendency to have more severe phenotypes with higher morbidity, showing its importance in TS prognosis. Additionally, we found rare genetic and phenotypic abnormalities associated with this syndrome. To the best of our knowledge, this is the first case of 45,X,t(11;12)(q22;q22) described as a TS karyotype. Turner patients usually have normal intelligence; however, moderate to severe levels of mental retardation were found in 5 TS cases, which is considerate a very uncommon feature in this syndrome.

Identification of a de novo inv dup(X)(pter--> q22) by multicolor banding in a girl with Turner syndrome.

We report on a 23-year-old girl with short stature, short and wide neck, low posterior hairline, hypogonadism, underdeveloped breasts, infantile uterus, ovaries not visualized, and primary amenorrhea. Cytogenetic G-banding analysis revealed a mosaic karyotype of 46,X,dup(X)(q22)[35]/45,X[15], confirming the clinical suspicion of Turner syndrome. Molecular cytogenetics using a multicolor banding probe set for the X-chromosome characterized an inverted dup(X). The karyotype of the patient was therefore interpreted as 46,X,inv dup(X) (pter --> q22::q22 --> pter). This patient had a mosaic Turner syndrome with a cell line comprising partial trisomy Xpter to Xq22 and partial monosomy Xq22 to Xqter.