Klinefelter syndrome is a chromosome disorder which affects males. A male usually has two chromosomes which determine his sex; there is an X chromosome inherited from his mother and a Y chromosome inherited from his father. A male with Klinefelter syndrome has an extra X chromosome.
Pathophysiology
Klinefelter syndrome is a chromosomal disorder which occurs when there is an extra X chromosome resulting in the karyotype 47, XXY. The male karyotype 46, XY would have an extra X chromosome. The disease pattern is usually caused by congenital aneuploidy of the sex chromosomes. 80% of individuals that have the 47, XXY karyotype (Nieschlag, 2013). The additional gene dosage of the X chromosome can lead to various complications such as long limbs, a tall stature, and a reduced upper/lower segment ration.
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Epidemiology
Klinefelter syndrome is usually the most common form of aneuploidy. It has an estimated prevalence of between 1:500 and 1:1000 males. Surveys of unselected newborn boys have also shown that there is an incidence of X-chromatin positive males between 1.1:1000 and 1.9:1000. Tabulated data from various centers showed that 37 out of 37,557 male newborns amounting to 0.09% (Los & Ford, 2018).
Physical exam findings
Physical examination on males with Klinefelter syndrome usually reveals small testicles. This is usually detected by genital examination. Other forms of physical examination identify physical symptoms associated with Klinefelter syndrome which is associated with less facial and body hair, breasts that are large than normal, less muscle tone with muscles growing slower than normal, and longer arms and legs with a shorter torso compared to other boys their age ("Klinefelter syndrome", 2017).
Differential diagnoses and medication plans
The differential diagnosis for Klinefelter syndrome can include a fragile X syndrome, Marfan syndrome, and Kallmann syndrome. Some individuals that have the syndrome also have other chromosome abnormalities such as Down syndrome (Rodrigues et al., 2017). There is no cure for Klinefelter syndrome. Treatment options are included to improve some aspects of the condition. Treatment options can include hormone therapy, reproductive technologies to aid fertility, cosmetic surgery, and counseling.
References
Los, E., & Ford, G. (2018). Klinefelter Syndrome. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK482314/#_article-23907_s4_
Nieschlag E. (2013). Klinefelter syndrome: the commonest form of hypogonadism, but often overlooked or untreated. Deutsches Arzteblatt international , 110 (20), 347-53.
Rodrigues, M. A., Morgade, L. F., Dias, L. F. A., Moreira, R. V., Maia, P. D., Sales, A. F. H., & Ribeiro, P. D. (2017). Down-Klinefelter syndrome (48, XXY, + 21) in a neonate associated with congenital heart disease. Genetics and Molecular Research , 16 (3).
Klinefelter syndrome. (2017). Retrieved from https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/klinefelter-syndrome
