Question

Differentiate between Mendelian and Chromosomal disorders.

Answer 1

Basis	Mendelian disorders	Chromosomal disorders
Cause	Mutation in a single gene (altered allele).	Abnormal number or structure of whole chromosomes (aneuploidy, deletions, translocations).
Pattern of inheritance	Follows Mendel’s single‑gene patterns dominant, recessive or sex‑linked.	Usually not simple Mendelian; often sporadic (e.g., from meiotic nondisjunction) and may not show typical parent‑to‑child Mendelian ratios.
Example	Cystic fibrosis, sickle cell single‑gene inheritance.	Down syndrome (trisomy 21) caused by nondisjunction leading to an extra chromosome.