Klinefelter-Syndrom

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

Epidemiology

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

Clinical presentation

the testes are normal prior to puberty and small in post pubertal testes; there is absent spermatogenesis
the kidneys may be symmetrically enlarged with small 1-8 mm cysts
post pubertal gynecomastia
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

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

Radiographic features

Klinefelter syndrome should be suspected in postpubertal males with bilateral symmetrical small testicular volume (usually 3~4 mL in volume) with ultrasonography, usually presented by subfertility/primary infertility or assessment of small testicular size and karyotyping should be recommended . However, Klinefelter syndrome is often overlooked or untreated.

Treatment and prognosis

Early recognition and hormonal treatment can improve quality of life and prevent serious complications. Testosterone replacement is mainly for androgen deficiency but does not improve infertility .