This site is targeted at medical and radiology professionals, contains user contributed content, and material that may be confusing to a lay audience. Use of this site implies acceptance of our Terms of Use.

Klinefelter syndrome

Dr Praveen Jha and Radswiki et al.

The Klinefelter syndrome (KS) is a chromosomal anomaly which in most cases is characterised by 47 chromosomes instead of the usual 46.

Epidemiology

The estimated incidence is at ~ 0.15 - 0.2% of live births.

Pathology

Genetics

~ 80 % have 47XXY
~ 10 % have mosaic 46XY / 47XXY
~ 10 % have 48XXYY and other less frequent types.

These abnormal divisions occur as sporadic events and are not hereditary.

Associations

Clinical features

the testes are normal prior to puberty and small in post pubertal testes - there is absent spermatogenesis
the kidneys can be symmetrically enlarged with small 1 - 8 mm cysts
post pubertal gynaecomastia
sparse facial and axillary hair
clinodactyly
tall stature
narrow shoulders
broad hips
normal to moderately reduced Leydig cell function
increased secretion of follicle-stimulating hormone
androgen deficiency
normal to slightly decreased verbal intelligence

Complications

increased incidence of male breast malignancy

Etymology

It is named after Harry Klinefelter who first described the syndrome in 1942.

This article is a stub, which means it needs more content. You can contribute to Radiopaedia.org too. Just register and edit... every little bit helps.