Question

Name the chromosomal disorder that is caused by the trisomy of the $21^{st}$ chromosome. Also write down its symptoms.

Hint:

Down's Syndrome was first described by Langdon Down in 1866.

Answer 1

Step 1: Understanding the Concept:
A chromosomal disorder occurs due to the gain or loss of one or more chromosomes. Trisomy means an individual has three copies of a specific chromosome instead of the usual pair.
Step 2: Detailed Explanation:
Disorder: Down's Syndrome is caused by the presence of an additional copy of chromosome number 21 (Trisomy 21).
Symptoms:
1. Physical features: Short stature with a small round head.
2. Facial features: Furrowed tongue and partially open mouth.
3. Hand features: Broad palm with a characteristic palm crease.
4. Development: Retarded physical, psychomotor, and mental development.
Step 3: Final Answer:
The disorder is Down's Syndrome. Key symptoms include physical and mental growth retardation, furrowed tongue, and characteristic facial features.