Turner syndrome

Definition

Turner syndrome is a chromosomal disorder that affects females, caused by the complete or partial absence of one of the two X chromosomes. This condition is characterized by various physical and developmental features, such as short stature, delayed puberty, and infertility. The impact of Turner syndrome is closely linked to variations in meiosis, specifically nondisjunction events that can lead to the absence or abnormality of sex chromosomes during gamete formation.

5 Must Know Facts For Your Next Test

1. Turner syndrome occurs in about 1 in 2,500 female births, making it one of the most common chromosomal disorders.
2. Individuals with Turner syndrome typically have a short stature, averaging about 4 feet 8 inches in adulthood, due to growth hormone deficiencies.
3. Many girls with Turner syndrome experience delayed puberty and may require hormone replacement therapy to develop secondary sexual characteristics.
4. In addition to physical features, Turner syndrome can also affect cognitive functions, although most individuals have normal intelligence.
5. Regular monitoring and medical care are important for managing associated health issues like heart defects and kidney abnormalities that can occur with Turner syndrome.

Review Questions

• How does nondisjunction during meiosis lead to Turner syndrome?
  • Nondisjunction is the process where chromosomes fail to separate properly during meiosis, resulting in gametes that contain an abnormal number of chromosomes. In the case of Turner syndrome, this often occurs when there is a missing or incomplete second X chromosome in the female's karyotype. When such a gamete participates in fertilization, it leads to the development of an embryo with Turner syndrome, characterized by the absence or alteration of one X chromosome.
• What are the common physical and developmental features associated with Turner syndrome, and how do these features relate to the genetic basis of the disorder?
  • Common features of Turner syndrome include short stature, delayed puberty, and infertility. These characteristics arise from the genetic basis of the disorder, primarily due to the loss of one X chromosome which carries genes crucial for growth and development. The absence of genes from this chromosome leads to hormonal imbalances and developmental delays. The interplay between genetics and phenotype makes understanding Turner syndrome essential for effective management and treatment.
• Evaluate the implications of early diagnosis and treatment for individuals with Turner syndrome in terms of their long-term health outcomes.
  • Early diagnosis and treatment of Turner syndrome can significantly improve long-term health outcomes for affected individuals. Interventions such as growth hormone therapy can help achieve a height closer to average by promoting growth during childhood. Additionally, hormone replacement therapy can assist in developing secondary sexual characteristics during puberty. Regular medical check-ups allow for monitoring potential health issues like cardiovascular defects and kidney problems. Overall, timely management fosters better physical and emotional health in individuals with Turner syndrome.

Related terms

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

Karyotype: A laboratory technique used to visualize an individual's complete set of chromosomes, allowing for the identification of chromosomal abnormalities such as Turner syndrome.

X-linked inheritance: A mode of genetic inheritance where a gene is located on the X chromosome; conditions can manifest differently in males and females due to their differing numbers of X chromosomes.