Semmelweis Medicine Biology Entrance Exam 2025 – 400 Free Practice Questions to Pass the Exam

Patau syndrome is primarily caused by trisomy 13, which means there are three copies of chromosome 13 instead of the usual two. This genetic anomaly leads to a wide range of developmental abnormalities and health issues, including severe intellectual disability, various physical deformities, and life-threatening medical conditions. The presence of an extra chromosome disrupts normal development, resulting in the characteristic features associated with Patau syndrome, such as facial abnormalities, polydactyly, and heart defects.

In contrast, the other chromosomal conditions listed are associated with different syndromes. Trisomy 21 is linked to Down syndrome, which involves developmental delays and distinctive physical traits. Klinefelter syndrome results from an extra X chromosome in males (XXY), leading to infertility and physical characteristics like reduced muscle tone. Turner syndrome, occurring in females, involves a missing or incomplete X chromosome, resulting in a variety of developmental issues and short stature. Each of these disorders has its unique set of genetic and phenotypic features, distinguishing them from Patau syndrome.