XVII: Congenital malformations, deformations and chromosomal abnormalities

Q90-Q99: Chromosomal abnormalities, not elsewhere classified

Chromosomal abnormalities refer to changes in the standard 23 pairs of human chromosomes that occur when there is an error during cell division, typically in the egg or sperm. This group of conditions can cause a variety of physical and intellectual anomalies. Chromosomal abnormalities can be inherited but more often they occur randomly during the formation of reproductive cells. Common types of chromosomal abnormalities include Down syndrome (trisomy 21), Turner syndrome (missing or incomplete X chromosome) and Klinefelter syndrome (an extra X chromosome in males). Symptoms can vary broadly depending on the specific type of abnormality but may include physical deformities, growth delays, learning disabilities and problems with the heart, brain, and other vital organs. The progression of these diseases can vary, some may worsen over time while others remain stable. Early diagnosis can help manage the symptoms and improve the quality of life of affected individuals.