Klinefelter’s syndrome, 47,XXY or XXY syndrome is a condition caused by a chromosome aneuploidy. Affected individuals have at least two X chromosomes and at least one Y chromosome. The extra X chromosome is retained because of a nondisjunction event during meiosis (sex cell division).
The XXY chromosome arrangement is one of the most common genetic variations from the XY karyotype, occurring in about 1 in 500 live male births.
- In adults, possible characteristics vary widely and include little or no indicatinon of affectedness, a lanky, youthful build and facial appearance, or a rounded body type with some degree of gynecomastia (increased breast tissue).
- Mean I.Q. between 85-90
- Affected males are almost always effectively sterile
- Some degree of language learning impairment may be present
- Hypogonadism, patients will often have a low serum testosterone level but high serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels.
- Microorchidism (i.e. small testicles)
- Increased risk of germ cell tumors, breast cancer, and osteoporosis
Although genetic variation is irreversible, symptoms associated with Klinefelter syndrome can be altered or treated in a number of ways, including the use of testosterone treatment