Trisomy

Definition

Trisomy is a genetic condition characterized by the presence of an extra chromosome in an individual's cells, resulting in a total of three copies of that chromosome instead of the usual two. This chromosomal abnormality can lead to various congenital disorders and birth defects, impacting development and overall health. Trisomy can occur with any chromosome but is most commonly associated with chromosomes 21, 18, and 13, leading to conditions such as Down syndrome, Edward syndrome, and Patau syndrome respectively.

5 Must Know Facts For Your Next Test

1. Trisomy 21, commonly known as Down syndrome, is the most frequent type of trisomy and occurs in approximately 1 in 700 live births.
2. Trisomy can happen due to non-disjunction during meiosis, which results in gametes with an abnormal number of chromosomes.
3. Individuals with trisomy often experience developmental delays, physical abnormalities, and increased risk of certain health issues.
4. Advanced maternal age is a significant risk factor for the occurrence of trisomy during pregnancy.
5. Prenatal screening tests can help detect trisomy early in pregnancy, allowing for better planning and care.

Review Questions

• How does non-disjunction lead to trisomy, and what are its implications for development?
  • Non-disjunction occurs when chromosomes fail to separate properly during meiosis, resulting in gametes with an abnormal number of chromosomes. When such a gamete participates in fertilization, the resulting zygote will have three copies of a specific chromosome instead of the usual two, leading to trisomy. This extra genetic material can disrupt normal development and cause various congenital disorders, highlighting the importance of understanding the mechanisms behind chromosomal abnormalities.
• Compare and contrast the common types of trisomy and their associated congenital disorders.
  • The three most common types of trisomy are Trisomy 21 (Down syndrome), Trisomy 18 (Edward syndrome), and Trisomy 13 (Patau syndrome). Each has distinct features: Trisomy 21 is characterized by developmental delays and characteristic facial features; Trisomy 18 presents with severe developmental issues and a high mortality rate within the first year; while Trisomy 13 involves multiple organ defects and severe intellectual disability. Understanding these differences helps in diagnosing and managing each condition effectively.
• Evaluate the impact of advanced maternal age on the incidence of trisomy, considering societal factors.
  • Advanced maternal age significantly increases the likelihood of non-disjunction events during oocyte formation, raising the risk for conditions like trisomy. As women choose to have children later in life due to various societal factors such as career considerations and financial stability, this trend leads to higher rates of chromosomal abnormalities. Public health education around these risks is essential for expectant mothers to make informed reproductive choices while addressing potential health implications for both mother and child.

Related terms

Aneuploidy: A genetic condition where an individual has an abnormal number of chromosomes, which includes conditions like trisomy or monosomy.

Chromosome: Structures within cells that contain DNA and genes; humans typically have 23 pairs of chromosomes.

Non-disjunction: The failure of homologous chromosomes or sister chromatids to separate properly during cell division, often leading to trisomy.