Monosomy

Definition

Monosomy is a type of chromosomal abnormality where there is a loss of one chromosome from a pair, resulting in a total of 45 chromosomes instead of the typical 46. This genetic condition can lead to various developmental and health issues, as the missing chromosome can disrupt normal gene function and protein production. Monosomy is often associated with specific syndromes and conditions, affecting physical and cognitive development.

5 Must Know Facts For Your Next Test

1. Monosomy typically results from nondisjunction during meiosis, where chromosomes fail to separate properly, leading to gametes with an abnormal number of chromosomes.
2. Turner Syndrome, caused by monosomy of the X chromosome, is one of the most common forms of monosomy, characterized by short stature, infertility, and various other physical features.
3. Individuals with monosomy may experience varying degrees of developmental delays, congenital anomalies, and health complications depending on which chromosome is missing.
4. Diagnosis of monosomy often involves chromosomal analysis through techniques like amniocentesis or chorionic villus sampling (CVS), allowing for early detection during pregnancy.
5. In some cases, monosomy may not be compatible with life, leading to miscarriage or stillbirth if critical chromosomes are missing.

Review Questions

• How does monosomy differ from other forms of aneuploidy like trisomy in terms of genetic implications?
  • Monosomy involves the loss of one chromosome from a pair, resulting in a total of 45 chromosomes, whereas trisomy involves the gain of an extra chromosome, leading to a total of 47. Both conditions are types of aneuploidy and can result in significant developmental issues; however, the effects can vary depending on which chromosome is affected. For example, while monosomy often leads to severe developmental disorders or conditions such as Turner Syndrome, trisomies like Down syndrome can result in different physical characteristics and cognitive challenges.
• What are the common clinical features associated with Turner Syndrome as a result of X chromosome monosomy?
  • Turner Syndrome arises from the complete or partial monosomy of the X chromosome and is characterized by several clinical features. These may include short stature, webbed neck, low-set ears, and heart defects. Additionally, individuals often experience delayed puberty due to ovarian dysgenesis leading to infertility. The condition requires careful management through hormone therapy and regular medical check-ups to address associated health issues.
• Evaluate the impact of prenatal screening techniques on the diagnosis and management of monosomy cases during pregnancy.
  • Prenatal screening techniques such as non-invasive prenatal testing (NIPT) and invasive procedures like amniocentesis have significantly improved the diagnosis of monosomy cases before birth. Early detection allows for informed decision-making for expectant parents regarding potential health outcomes for their child. Moreover, it provides opportunities for early intervention strategies post-birth, which can improve quality of life. However, these screenings also raise ethical considerations regarding choices made after receiving such information about chromosomal abnormalities.

Related terms

Aneuploidy: Aneuploidy refers to an abnormal number of chromosomes in a cell, which can include monosomy (loss of one chromosome) or trisomy (gain of one chromosome).

Turner Syndrome: Turner Syndrome is a genetic disorder caused by monosomy of the X chromosome, affecting females and leading to various developmental challenges.

Karyotype: A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell, used to identify chromosomal abnormalities like monosomy.