Embryology Problem Based Question (Q3 - Langman)

ANATOMY AIIMS, GROSS ANATOMY, EMBRYOLOGY, NEUROANATOMY, MICROANATOMY, APPLIED/ CLINICAL ANATOMY

What is the most common cause of abnormal chromosome number? Give an example of a clinical syndrome involving abnormal numbers of chromosomes.

Answer:

The most common cause of abnormal chromosome number is non-disjunction during cell division, which results in the unequal distribution of chromosomes between daughter cells. Non-disjunction can occur during both meiosis and mitosis, leading to an abnormal number of chromosomes in the resulting cells.

During meiosis, non-disjunction can lead to aneuploidy, which is an abnormal number of chromosomes in the resulting gamete. Aneuploidy can result in various clinical syndromes, such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13).

Down syndrome is the most common example of a clinical syndrome involving abnormal numbers of chromosomes. It occurs due to the presence of an extra copy of chromosome 21. Down syndrome is characterized by distinct facial features, intellectual disability, and an increased risk of certain health conditions such as heart defects and Alzheimer's disease.

Reference:

Sadler, T. W. (2019). Langman's medical embryology (14th ed.). Wolters Kluwer.