48,XXYY, 48,XXXY and 49,XXXXY syndromes: not just variants of Klinefelter syndrome
Article first published online: 8 APR 2011
© 2011 The Author(s)/Acta Pædiatrica © 2011 Foundation Acta Pædiatrica
Volume 100, Issue 6, pages 851–860, June 2011
How to Cite
Tartaglia, N., Ayari, N., Howell, S., D’Epagnier, C. and Zeitler, P. (2011), 48,XXYY, 48,XXXY and 49,XXXXY syndromes: not just variants of Klinefelter syndrome. Acta Paediatrica, 100: 851–860. doi: 10.1111/j.1651-2227.2011.02235.x
- Issue published online: 27 APR 2011
- Article first published online: 8 APR 2011
- Accepted manuscript online: 22 FEB 2011 12:09PM EST
- Received 12 October 2010; revised 31 January 2011; accepted 16 February 2011.
- Klinefelter syndrome;
- XXXXY syndrome;
- XXXY syndrome;
- XXYY syndrome
Sex chromosome tetrasomy and pentasomy conditions occur in 1:18 000–1:100 000 male births. While often compared with 47,XXY/Klinefelter syndrome because of shared features including tall stature and hypergonadotropic hypogonadism, 48,XXYY, 48,XXXY and 49,XXXXY syndromes are associated with additional physical findings, congenital malformations, medical problems and psychological features. While the spectrum of cognitive abilities extends much higher than originally described, developmental delays, cognitive impairments and behavioural disorders are common and require strong treatment plans. Future research should focus on genotype–phenotype relationships and the development of evidence-based treatments.
Conclusion: The more complex physical, medical and psychological phenotypes of 48,XXYY, 48,XXXY and 49,XXXXY syndromes make distinction from 47,XXY important; however, all of these conditions share features of hypergonadotropic hypogonadism and the need for increased awareness, biomedical research and the development of evidence-based treatments.