Klinefelter syndrome

Klinefelter syndrome (KS) is a sex chromosomal anomaly, which in most cases is characterised 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 canmay 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

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

• omphalocoeleomphalocele
• choroid plexus cysts

Radiographic features

Klinefeltersyndrome should be suspected in postpubertal males with bilateral symmetrical small testicular volume (usually 3~4 mlmL in volume) with ultrasonography, usually presented by subfertility / primary/primary infertility or assessment of small testicular size and karyotyping should be recommended ⁷. 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 doesn'tdoes not improve infertility ⁷. 

Complications

• increased incidence of male breast malignancy
• increased incidence of germ cell tumors, particularly in the mediastinum ⁶.

History and etymology

It is named after Harry Klinefelter (1912-1990) ⁸ who first described the syndrome in 1942.