Genetic Disorders

Genetic disorders of the sex chromosome (like disorders of the autosomes) can be either numerical or structural, and can be present in all cells or in a mosaic form. Samples can be referred for a wide variety of reasons (see below):

 

Klinefelter Syndrome

If a patient is suspected of Klinefelter syndrome which is a condition where human males have an extra X chromosome. Males normally have a chromosomal makeup of XY, but an affected individual with Klinefelter syndrome will have at least two X chromosomes and at least one Y chromosome. The phenotype of the affected person is basically male, tall stature with elongated lower legs and forearms. The body shape, however, is more feminine (narrow shoulders, broad hips) with a lower muscle mass. The risk for male breast cancer and osteoporosis is also increased. One of the main symptoms of Klinefelter Syndrome is infertility that arises in the beginning of the third decade at its latest. The infertility is a result of atrophy of the seminiferous tubules. The testicles and penis of an affected man are small (< 10 mL, 2 cm), and the individual also express low libido and impotence.

 

Turner syndrome (TS)

If a patient is suspected of Turner syndrome (TS) which is the most common sex chromosome disorder with an incidence of 1/2500 live-born females. Turner syndrome occurs with a similar frequency in all populations. Turner syndrome is a developmental disorder and is caused by the absence or structural abnormality of a sex chromosome, typically an X chromosome. This syndrome is an instance of monosomy, and it is the only one that is not lethal, once the child is born. Women with Turner syndrome currently have limited reproductive options. In 2% of women, spontaneous pregnancy can occur.

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