Monosomy X (45,X); Ullrich-Turner syndrome
Turner syndrome (TS) is a genetic disorder appearing in females, caused by a complete or partial absence of one of the X chromosomes that manifests in variable phenotypic features including short stature, endocrine deficiency, cardiac and renal anomalies, and neurocognitive and behavioral challenges.
Variants of TS are classified on the basis of results from cytogenetic testing, which can reveal sex chromosome abnormalities by means of a karyotype (Davenport et al. 2007). Approximately half of the females diagnosed with TS have a complete absence of one of the X chromosomes, termed monosomy X (45,X). Other structural variants found in individuals with TS include duplication (isochromosome) of the long arm of one X chromosome i(Xq), long-arm deletion (Xq-), small distal short-arm deletions (Xp-), and ring X. Mosaicism is frequently observed, where some cells are missing an X chromosome (45,X), while one or...
References and Readings
- Davenport, M. L., Hooper, S. R., & Zeger, M. (2007). Turner syndrome in childhood. In M. M. M. Mazzocco & J. L. Ross (Eds.), Neurogenetic developmental disorders: Variation of manifestation in childhood (pp. 3–45). Cambridge, MA: MIT Press.Google Scholar
- Gravholt, C. H., Andersen, N. H., Conway, G. S., Dekkers, O. M., Geffner, M. E., Klein, K. O., Lin, A. E., Mauras, N., Quigley, C. A., Rubin, K., Sandberg, D. E., Sas, T. C. J., Silberbach, M., Soderstrom-Anttila, V., Stochholm, K., van Alfen-van der Velden, J. A., Woelfle, J., Backeljauw, P. F., & International Turner Syndrome Consensus, G. (2017). Clinical practice guidelines for the care of girls and women with Turner syndrome: Proceedings from the 2016 Cincinnati International Turner Syndrome Meeting. European Journal of Endocrinology of the European Federation of Endocrine Societies, 177(3), G1–G70.CrossRefGoogle Scholar
- Green, T., Naylor, P. E., & Davies, W. (2017). Attention deficit hyperactivity disorder (ADHD) in phenotypically similar neurogenetic conditions: Turner syndrome and the RASopathies. Journal of Neurodevelopmental Disorders, 9, 25. https://doi.org/10.1186/s11689-017-9205-xCrossRefPubMedCentralPubMedGoogle Scholar
- Kornman, L., Palma-Dias, R., Nisbet, D., Scott, F., Menezes, M., da Silva Costa, F., & McLennan, A. (2017). Non-invasive prenatal testing for sex chromosome aneuploidy in routine clinical practice. Fetal Diagnosis and Therapy. https://doi.org/10.1159/000479460CrossRefPubMedPubMedCentralGoogle Scholar
- Mazzocco, M. M. M., Quintero, A., Murphy, M. M., & McCloskey, M. (2015). Genetic syndromes as model pathways to mathematical learning difficulties: Fragile X, Turner, and 22q deletion syndromes. In D. B. Berch, D. B Geary & K. Mann-Koepke (Eds.), Development of mathematical cognition: Neural substrates and genetic influences (pp. 325–357). San Diego, CA: Elsevier/Academic Press.CrossRefGoogle Scholar