Related articles: Klinefelter syndrome
Definition
Klinefelter syndrome is one of the most common forms of aneuploidy (ie an anomaly in the number of chromosomes). This disease, in particular, is characterized by the presence of additional copies of the genes present on the X chromosome, which interfere with normal male sexual development.
In fact, in fact, male subjects possess a pair of sex chromosomes (X and Y) and 22 pairs of non-sexual chromosomes, for a total of 46 chromosomes (46, XY). In most cases, individuals with Klinefelter syndrome have a supernumerary copy of the X chromosome in all cells of the body (classic variant: 47, XXY) or only in some cells (mosaicism: 46, XY / 47, XXY).
Klinefelter syndrome is not hereditary, but arises spontaneously due to the lack of meiotic disjunction of chromosomes during gametogenesis. The only risk factor currently known for this error in cell division is advanced maternal age.
Most common symptoms and signs *
- Testicular atrophy
- Azoospermia
- clinodactyly
- Learning difficulties
- Difficulty concentrating
- Language difficulties
- Dysarthria
- Erectile dysfunction
- Gynecomastia
- infertility
- Microcephaly
- Mental delay
Further indications
Klinefelter syndrome is a disorder characterized by testicular hypotrophy, excessive breast development (gynecomastia), hypogonadism, hormonal imbalances (high FSH concentrations and insufficient testosterone production) and poor virilization. These conditions cause infertility (main symptom of the syndrome) and azoospermia (lack of sperm production).
Other symptoms include abnormal body proportions (reduced head circumference, long legs, short trunk, broad shoulders such as the hips, high stature and poor muscular development) and neurological and cognitive disorders, with predisposition to problems of verbal learning, expressiveness and dysarthria. Often, affected boys may have small testicles (testicular atrophy) and increased consistency. Puberty usually occurs at the usual age, but often the growth of hair on the face is scarce and the distribution of fat is of the female type (ginoid adiposity).
Furthermore, subjects with Klinefelter syndrome have overweight, increased risk of osteoporosis, autoimmune thyroid disorders and type 2 diabetes mellitus.
Finally, in these patients there is an increased incidence of some tumors such as: breast cancer, acute lymphatic leukemia and germ cell neoplasms.
Many cases are diagnosed in adulthood, during an assessment to identify the causes of infertility. Klinefelter syndrome can be defined with certainty only by cytogenetic analysis, ie through the study of chromosomes. With the increase in the number of X chromosomes, the severity of intellectual disability and malformations also increases.
