Trisomy

Trisomy. Type of chromosome mutation where an individual has three homologous chromosomes instead of a pair (2n+1). The cause of trisomy is the failure of homologous chromosomes to separate during meiosis (in the case of asexual reproduction – mitosis). Trisomy occurs in both plants and animals. Such mutations in animals are usually lethal. Individuals who survive have physical and mental disorders, called syndromes. The most common case of trisomy among humans is Down syndrome – trisomy of chromosome 21. In cases of trisomy of other chromosomes, infants die before birth or even in very early stages of pregnancy (miscarriage). Also quite common are trisomies of the X sex chromosome.

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė