Klinefelter Syndrome

Klinefelter syndrome is a genetic condition caused by an extra ‘X’ sex chromosome. It’s an issue for about 1 in 500-1,000 newborn boys. While it’s not an inherited condition, women over 35 are slightly more likely to have boys with this syndrome than younger mothers.

All our genetic material is sequences of DNA held on 46 chromosomes. The chromosomes are identical between the sexes except for the ‘X’ or ‘Y’ chromosomes, which determine our sex:

Two X chromosomes are normal for females.
One X and one Y chromosome are standard for males.
In Klinefelter syndrome, the boys and men have ‘XXY’ due to an extra X chromosome.

Many Klinefelter syndrome boys show no symptoms or may show some of the possible symptoms after puberty. While the symptoms may vary between individuals, the condition makes all Klinefelter syndrome men infertile without specialist help.

Symptoms

Abnormal body proportions (long legs, short trunk, broad hips) and tall.
Muscle weakness, weaker bones, and a lower energy level than other boys. ⁱ
Abnormally large breasts and small, firm testes.
Infertility.
A lack of interest in sex or sexual problems.
Little pubic, armpit or facial hair.

Testing

Infertility is often why a man gets diagnosed with Klinefelter syndrome, and Klinefelter syndrome men won’t have any sperm in their semen samples. Blood hormonal tests will show:

Raised levels of estradiol (one of the estrogens).
Raised follicle-stimulating hormone (FSH) levels.
Raised luteinizing hormone (LH) levels.
Low levels of testosterone.

The definitive test is a chromosome (karyotype) test that shows the extra X chromosome.

Treatment

The genetic variation that causes the condition is irreversible. However, testosterone treatment is an option for those who wish for a more masculine appearance and identity. It will increase body hair, energy and sex drive and improve mood and concentration.

As far as fertility is concerned, Klinefelter men are unable to have children without specialist sperm-retrieval techniques. These have made it possible for men with Klinefelter syndrome to father a child, and by 2010 there were over 100 successful pregnancies following IVF that used surgically-recovered sperm material from men with Klinefelter syndrome. ⁱⁱ

ⁱ http://www.nichd.nih.gov/health/topics/klinefelter_syndrome.cfm
^{ii “}Should non-mosaic Klinefelter syndrome men be labelled as infertile in 2009?”. Fullerton G, Hamilton M, Maheshwari A. (2010). Hum Reprod. 2010 Mar;25(3):588–97.