Talk:Trisomy X
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Cite this page: Hill, M.A. (2024, April 18) Embryology Trisomy X. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Trisomy_X |
Karyotype image - http://www.biology.iupui.edu/biocourses/N100/images/XXXFemale.gif
2010
A review of trisomy X (47,XXX)
Orphanet J Rare Dis. 2010 May 11;5:8.
Tartaglia NR, Howell S, Sutherland A, Wilson R, Wilson L. Source Department of Pediatrics, University of Colorado Denver School of Medicine, 13123 East 16th Ave., Aurora, CO 80045, USA. tartaglia.nicole@tchden.org Abstract Trisomy X is a sex chromosome anomaly with a variable phenotype caused by the presence of an extra X chromosome in females (47,XXX instead of 46,XX). It is the most common female chromosomal abnormality, occurring in approximately 1 in 1,000 female births. As some individuals are only mildly affected or asymptomatic, it is estimated that only 10% of individuals with trisomy X are actually diagnosed. The most common physical features include tall stature, epicanthal folds, hypotonia and clinodactyly. Seizures, renal and genitourinary abnormalities, and premature ovarian failure (POF) can also be associated findings. Children with trisomy X have higher rates of motor and speech delays, with an increased risk of cognitive deficits and learning disabilities in the school-age years. Psychological features including attention deficits, mood disorders (anxiety and depression), and other psychological disorders are also more common than in the general population. Trisomy X most commonly occurs as a result of nondisjunction during meiosis, although postzygotic nondisjunction occurs in approximately 20% of cases. The risk of trisomy X increases with advanced maternal age. The phenotype in trisomy X is hypothesized to result from overexpression of genes that escape X-inactivation, but genotype-phenotype relationships remain to be defined. Diagnosis during the prenatal period by amniocentesis or chorionic villi sampling is common. Indications for postnatal diagnoses most commonly include developmental delays or hypotonia, learning disabilities, emotional or behavioral difficulties, or POF. Differential diagnosis prior to definitive karyotype results includes fragile X, tetrasomy X, pentasomy X, and Turner syndrome mosaicism. Genetic counseling is recommended. Patients diagnosed in the prenatal period should be followed closely for developmental delays so that early intervention therapies can be implemented as needed. School-age children and adolescents benefit from a psychological evaluation with an emphasis on identifying and developing an intervention plan for problems in cognitive/academic skills, language, and/or social-emotional development. Adolescents and adult women presenting with late menarche, menstrual irregularities, or fertility problems should be evaluated for POF. Patients should be referred to support organizations to receive individual and family support. The prognosis is variable, depending on the severity of the manifestations and on the quality and timing of treatment.
PMID 20459843
X trisomy in a sterile mare
Equine Vet J. 2010 Jul;42(5):469-70.
de Lorenzi L, Molteni L, Zannotti M, Galli C, Parma P.
Department of Animal Science, Milan University, Italy. Abstract This report concerns the cytogenetic analysis, using both C-banding and fluorescence in situ hybridisation techniques, of a sterile mare. Results obtained revealed a 2n = 65, XXX condition with no sign of mosaicism. The work supports the suggestion that X trisomy, rare in horse, causes infertility in mares and is not associated to other clearly visible phenotypic features.
PMID 20636786
