Background
Medical Management Considerations
References
Resources for Families
Advisory Committee
Publication Information
Learning Points
BACKGROUND
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Description and Causes
XYY syndrome is the condition in which males have two Y chromosomes and the chromosome constitution 47,XYY rather than the usual one Y chromosome. Discovered in 1961 by Sandberg and co-workers, newborn boys with XYY exhibit no special physical stigmata except for increased height. No definite causes of the chromosome aberration have been identified.
Boys with XYY syndrome often are more physically active than other males. If this activity is channeled into play, sports or other physical activities, this fact is in no way negative. Boys with XYY syndrome have a tendency to delayed mental maturation and an increased tendency for learning problems in school.
XYY boys commonly develop normally in childhood, and their intelligence is usually within the normal range. Their increased growth velocity is evident during the earliest childhood.
Physical sexual development is normal, with normal development of sex organs and of secondary sex characteristics. Puberty appears at the expected time, and XYY males are fertile in spite of somewhat decreased sperm quality with many “immature” sperm cells.
XYY males do not demonstrate an increased risk of diseases in childhood or adulthood. Very rarely are sons of XYY males XYY themselves.
Diagnosis
Karyotyping can confirm XYY syndrome; however, XYY males neither look nor behave in a manner which would prompt testing for chromosome abnormality. The most common indication for an XYY male to be karyotyped will be developmental delay and/or behavior problems. Generally diagnosed when prenatal karyotyping is done for the detection of Down syndrome and other major aneuploidies, most XYY males will go through life without being karyotyped.
Occurrence
Characteristic Features
Common Associations
Several case reports suggest an association between XYY syndrome and renal agenesis or cystic dysplasia of the kidney leading to Potter sequence (Rudnick-Schoneborn et al. 1996).
Some support for hypothesis that a loss of balance of gene products on the sex chromosomes, possibly including XYY syndrome, may predispose affected individuals to susceptibility to additional genetic and environmental insults that result in childhood-onset psychotic disorders (Kumra et al. 1998).
MEDICAL MANAGEMENT CONSIDERATIONS
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Note: These considerations are in addition to the normal medical care provided to an individual without XYY syndrome. All recommendations can be addressed through clinical examination by the primary care provider, unless otherwise noted.
Ongoing
Infancy of Early Childhood (Birth to 5 years)
Late Childhood (5 to 13 years)
Adolescence and Adulthood (13 years and over)
REFERENCES
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Peer-reviewed Journal Articles/Academies
Abramsky, L., Chapple, J. (1997). 47,XXY (Klinefelter Syndrome) and 47,XYY: Estimated Rates of and Indication for Postnatal Diagnosis with Implications for Prenatal Counseling. Prenatal Diagnosis, 17(4), 363-368.
Gron, M., Pietila, K., Alvesalo, L. (1997). The Craniofacial Complex in 47,XYY Males. Archives of Oral Biology, 42(8), 579-586.
Kumra, S., Wiggs, E., Krasnewich, D., Meck, J., Smith, A. C., Bedwell, J., Fernandez, T., Jacobsen, L. K., Lenane, M., and Rapoport, J. L. (1998). Brief Report: Association of Sex Chromosome Anomalies with Childhood-onset Psychotic Disorders. Journal of the American Academy of Child and Adolescent Psychiatry, 37(3), 292-296.
Rudnik-Schoneborn, S., Schuler, H.M., Schwanitz, G., Hansmann, M., Zerres, K. (1996). Further Arguments for Non-fortuitous Association of Potter Sequence with XYY Males. Annals of Human Genetics, 39(1), 43-46.
Theilgaard, A. (1984). A psychological study of the personalities of XYY and XXY men. Acta Psychiatrica Scandinavica 69: 315, 133.
Special Interest Groups/Other Publications
National Organization for Rare Disorders
PO Box 8923
New Fairfield, CT 06812-8923
(203) 746-6518
E-mail: [email protected]
March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
(914) 428-7100
(888) 663-4637
E-mail: [email protected]
RESOURCES FOR FAMILIES
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Johannes Nielsen
Cytogenetic Laboratory
Ã…rhus Psychiatric Hospital
DK-8240 Risskov
Denmark
86-17-77-77, x 549
UNIQUE – Rare Chromosome Disorder Support Group
PO Box 2189 Caterham
Surrey, CR3-5GN
United Kingdom
(018) 83-330766
E-mail: [email protected]
ADVISORY COMMITTEE
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Theodore A. Kastner, M.D., M.S.
Felice Weber Parisi, M.D., M.P.H.
Patricia Samuelson, M.D.
Mary Tierney, M.D.
PUBLICATION INFORMATION
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This document does not provide advice regarding medical diagnosis or treatment for any individual case, and any opinions or statements contained in this document are not intended to serve as a standard of medical care. Physicians are encouraged to view the considerations presented in this document in light of evolving scientific information. This document is not intended for use by the layperson. Reproduction of this document may be done with proper credit given to California Department of Developmental Services.