Down syndrome

Definition

Down syndrome is a genetic disorder caused by the presence of an extra chromosome 21, leading to physical and intellectual disabilities. This chromosomal aberration, known as trisomy 21, results from nondisjunction during cell division, where chromosomes fail to separate properly. The condition is characterized by distinct facial features, developmental delays, and a higher risk for certain health issues.

5 Must Know Facts For Your Next Test

1. Down syndrome occurs in approximately 1 in 700 live births, making it one of the most common chromosomal conditions.
2. Individuals with Down syndrome typically exhibit distinct physical characteristics, such as a flat facial profile, slanted eyes, and a single transverse palmar crease.
3. Many individuals with Down syndrome have mild to moderate intellectual disabilities, but with early intervention and educational support, they can lead fulfilling lives.
4. Health complications often associated with Down syndrome include congenital heart defects, respiratory issues, and an increased risk for certain cancers.
5. Down syndrome can be diagnosed before birth through prenatal screening and diagnostic tests such as amniocentesis or chorionic villus sampling.

Review Questions

• How does nondisjunction contribute to the development of Down syndrome?
  • Nondisjunction is the process that leads to the improper separation of chromosomes during cell division. In the case of Down syndrome, it results in an extra copy of chromosome 21, leading to trisomy 21. This extra genetic material disrupts normal development and causes the characteristic features and health issues associated with Down syndrome.
• Discuss the impact of early intervention on individuals with Down syndrome in terms of developmental outcomes.
  • Early intervention is crucial for individuals with Down syndrome as it provides them with essential support and resources during their formative years. Programs focusing on speech therapy, occupational therapy, and special education can significantly enhance cognitive and motor skills. Research shows that children who receive early intervention are more likely to achieve better social integration and independence in adulthood compared to those who do not receive such support.
• Evaluate the ethical considerations surrounding prenatal screening for Down syndrome and the implications it has for expectant parents.
  • Prenatal screening for Down syndrome raises important ethical questions regarding parental choice and the value placed on lives affected by disabilities. While these screenings can provide parents with valuable information about their unborn child’s health, they also lead to discussions about potential decisions regarding continuation of the pregnancy. The implications are profound; they touch upon societal attitudes towards disability, informed consent, and the potential for discrimination against individuals with Down syndrome. This complex issue necessitates careful consideration by healthcare providers and expectant parents alike.

Related terms

Chromosomal aberration: A mutation or alteration in the structure or number of chromosomes, which can lead to genetic disorders.

Nondisjunction: The failure of homologous chromosomes or sister chromatids to separate properly during cell division, resulting in an abnormal number of chromosomes.

Trisomy: A type of chromosomal abnormality where there are three copies of a particular chromosome instead of the usual two.