Trisomy

Definition

Trisomy is a genetic disorder where an individual has three copies of a chromosome instead of the usual two. This can lead to developmental and physical abnormalities.

5 Must Know Facts For Your Next Test

1. Trisomy 21, also known as Down syndrome, is the most common form of trisomy.
2. Trisomy can result from nondisjunction during meiosis, leading to an extra chromosome in the gametes.
3. Individuals with trisomy often exhibit symptoms such as developmental delays and distinct facial features.
4. Prenatal screening techniques like amniocentesis and chorionic villus sampling can detect trisomies.
5. Other forms of trisomy include Trisomy 13 (Patau syndrome) and Trisomy 18 (Edwards syndrome), both of which are usually more severe than Down syndrome.

Review Questions

• What is the primary cause of trisomy at the cellular level?
• Which form of trisomy is associated with Down syndrome?
• What are two prenatal diagnostic techniques that can identify trisomies?

Related terms

Nondisjunction: The failure of chromosomes to separate properly during cell division, leading to cells with abnormal chromosome numbers.

Down Syndrome: A genetic disorder caused by Trisomy 21, characterized by intellectual disability and distinct physical features.

Amniocentesis: A prenatal diagnostic procedure where amniotic fluid is sampled to test for chromosomal abnormalities.