Klinefelter Syndrome and Turner Syndrome

Carole Samango-Sprouse, EdD *, †, ‡ Sophia Q. Song, BA ‡ Angela E. Lin, MD§ Cynthia M. Powell, MD¶ Andrea L. Gropman, MD *, *** George Washington University, Washington, DC † Florida International University, Miami, FL ‡ Department of Research, The Focus Foundation, Davidsonville, MD§ Massachusetts General Hospital for Children, Boston, MA¶ University of North Carolina at Chapel Hill, Chapel Hill, NC ** Children’s National Medical Center, Washington , DC


Samango-Sprouse, Lin, Powell, and Gropman and Ms. Song have not disclosed any financial relationships relevant to this article. This comment does not include a discussion of an unapproved / investigational use of a commercial product / device.

Sex chromosome anuploidy (SCA) syndromes refer to disorders with an abnormality in the number of sex chromosomes. The most common are Klinefelter syndrome (KS), which results from the increase in an X chromosome in men, and Turner syndrome (TS), which is the loss of an X chromosome or the presence of a structurally different X chromosome in women. While most patients with KS have non-mosaic 47, XXY, only 40% of women with TS have 45, X; the rest has a variety of mosaics. The syndromes also contrast in that men with KS are characteristically tall, while women with TS are generally short unless they receive hormonal treatment.

Despite efforts to raise awareness, KS and TS are often underdiagnosed, leading to delayed care. Only 25% of men with KS are ever diagnosed, with less than 10% detected prenatally, and with a median age of 27 years for those identified later in life. For TS, the median age at diagnosis is 6.6 years. While not exclusively, optimal neurocognitive outcomes depend on the timing of diagnosis and access to early targeted treatment, so fortunately the recent development of non-invasive prenatal screening is dramatically increasing the early identification of these conditions. Pediatricians need to be aware of signs that allow early detection and the importance of prompt referral for testing and therapy.

KS occurs in 1 in 660 live births, which is the most common cardiac arrest. Affected men have androgen deficiency, which affects endocrine, central nervous system and neurodevelopmental function. Features include increased height, fifth finger clinodactyly, pes planus, and hypogonadism manifesting as …

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