Klinefelter’s syndrome

Klinefelter’s syndrome is a chromosomal disorder in which men have at least one extra X chromosome. The most common karyotype for Klinefelters is XXY

Characteristics of Klinefelter’s syndrome include:

• Small testes
• Gynaecomastia
• Tall stature
• Azoospermia
• Sparse facial and body hair
• Possibly learning difficulties

Blood tests show

• Low testosterone
• High LH/FSH

Around 1 in 500 men are affected, making it the most common disorder of sex chromosomes.

Associations:

• increased risk of breast cancer
• endocrine problems - diabetes, hypothyroidism
• autoimmune conditions - SLE, RA
• osteoporosis – 25%

Treatment: testosterone replacement therapy

References:

Radicioni, A. et al. Strategies and advantages of early diagnosis in Klinefelter’s syndrome. Mol Hum Reprod. 2010; 16(6): 434-440.

Visootsak, J. and Graham, J. Klinefelter syndrome and other sex chromosomal aneuploidies. Orphanet J Rare Dis. 2006; 24: 42.