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Practice Easily Missed?

Klinefelter’s syndrome

BMJ 2012; 345 doi: (Published 03 December 2012) Cite this as: BMJ 2012;345:e7558
  1. Christopher H Blevins, resident physician1,
  2. Michael E Wilson, instructor of medicine1
  1. 1Mayo Clinic Department of Medicine, 200 First Street SW, Rochester, Minnesota, MN 55905, USA
  1. Correspondence to: M E Wilson wilson.michael1{at}
  • Accepted 26 October 2012

A 29 year old man presented to primary care with anxiety and depression that had worsened since childhood. Further questioning revealed a history of poor school performance, poor body image, and poor self esteem. On physical examination, the patient’s height was 189 cm and he had narrow shoulders, wide hips, sparse facial hair (which he shaved once every two months), and small, firm testicles. He was found to have elevated luteinising hormone and follicular stimulating hormone concentrations, low serum concentrations of testosterone, absent sperm on semen analysis, and a karyotype of 47,XXY.

What is Klinefelter’s syndrome?

Klinefelter’s syndrome is the clinical result of an additional X chromosome in males (47,XXY), although other chromosome abnormalities (such as 46,XY/47,XXY mosaicism; 48,XXXY; 49,XXXXY) account for 10-20% of cases.1 2 Classic clinical findings include infertility, small testes, hypergonadotropic hypogonadism (elevated luteinising hormone and follicular stimulating hormone concentrations with low or low to normal testosterone concentrations), decreased facial and body hair, gynecomastia, tall stature with eunuchoid features, and psychosocial morbidity.1 3

How common is Klinefelter’s syndrome?

  • Klinefelter’s syndrome affects 1 in 667 live male births and is the most common sex chromosome disorder4

  • Large population based studies confirm that more than 90% of boys with Klinefelter’s syndrome aged 10-14 years and about 75% of men with the syndrome aged 25-54 …

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