Aneuploidy

Aneuploidy is a condition characterized by an abnormal number of chromosomes in a cell. Unlike euploidy, where cells contain the correct multiple of the haploid number (n) of chromosomes, Aneuploidy involves either the gain or loss of individual chromosomes. This numerical chromosome abnormality can arise from errors during cell division, particularly meiosis and mitosis, and can lead to a variety of genetic disorders. Aneuploidy can affect autosomes (non-sex chromosomes) or sex chromosomes, influencing phenotypic traits and development. It often results in developmental abnormalities, spontaneous abortions, and various syndromes.

Aneuploidy meaning with examples

• Down syndrome, or Trisomy 21, is a classic example of aneuploidy. Individuals with this condition have three copies of chromosome 21 instead of the normal two. This chromosomal abnormality leads to characteristic physical features and intellectual disabilities. Prenatal screening often aims to detect aneuploidy.
• Turner syndrome, caused by monosomy X, is a form of Aneuploidy affecting females. Affected individuals have only one X chromosome, leading to a range of developmental challenges, including short stature and ovarian insufficiency. The presence of Aneuploidy affects hormone regulation and fertility.
• Klinefelter syndrome, characterized by an extra X chromosome in males (XXY), is a sex chromosome aneuploidy. It can cause infertility, reduced muscle mass, and cognitive challenges. The prevalence of Aneuploidy varies in population and can stem from nondisjunction.
• In some cancers, somatic Aneuploidy (aneuploidy in non-germ cells) is a common feature. The altered number of chromosomes in tumor cells can contribute to uncontrolled cell growth and the development of resistance to therapy. Targeting Aneuploidy is a focus of cancer research.
• Patau syndrome, or Trisomy 13, is another example of autosomal aneuploidy. Babies with Patau syndrome often experience severe birth defects and have a very low survival rate due to multiple organ system defects. This condition arises due to chromosomal non-disjunction.