Klinefelter syndrome is a chromosomal pathology characterized by the presence of an additional X chromosome in an individual's cells (only boys can be affected).
The parents of the child are healthy individuals with no relation to the syndrome. During maturation, in some of the parents' germ cells, the X chromosomes may "stick" together, and if conception occurs with this cell, the boy's genotype will be XXY instead of XY as normal. It is also possible for chromosomes not to separate at an early stage of development of a normally fertilized egg.
From 3 to 5% of pregnancies carry a genetic pathology. However, modern diagnostic tools allow for the recognition of most pathologies at an early stage of pregnancy and prevent the birth of an affected child.
Treatment of Klinefelter Syndrome
The manifestation of symptoms can be alleviated by administering male sex hormones, which begins at puberty.
Prenatal Diagnosis
There are screening tests that allow for the assessment of the risk of carrying a fetus with Klinefelter syndrome based on the analysis of the concentration of plasma protein A and the beta-subunit of chorionic hormone in the mother's blood. Adjusting for age, the relative risk is calculated, and if a certain age parameter is exceeded, a biopsy of the fetal tissues is performed. At 8-12 weeks – chorionic biopsy, at 14-18 weeks – amniocentesis, after 20 weeks – cordocentesis. Based on karyotyping – the creation of a chromosomal map, a decision is made regarding medical abortion to prevent the birth of an affected child.
Modern diagnostic methods also include polymerase chain reaction (PCR) – a quick, effective method of testing. However, it should be noted that PCR has a significant percentage of misdiagnosis in mosaic cases – the error rate in diagnosing a fetus that has a mixed, normal, and pathological genotype.