Q.42 Match the genetic disorder (Column I) with its molecular basis (Column II)
Column I                                                                Column II
P. Sickle-cell anemia                                          1. Mutation in nucleotide excision repair
Q. Xeroderma pigmentosum                           2. Trisomy of chromosome 21
R. Tay-Sachs disease                                         3. Mutation in β-globin gene
S. Down Syndrome                                            4. Mutation in hexosaminidase A gene
(A) P-1; Q-4; R-2; S-3
(B) P-3; Q-4; R-1; S-2
(C) P-3; Q-1; R-4; S-2
(D) P-4; Q-2; R-3; S-1

Unlocking Genetic Disorders: Matching Sickle-Cell Anemia, Xeroderma Pigmentosum, Tay-Sachs, and Down Syndrome with Molecular Causes

Sickle-cell anemia links to a β-globin gene mutation, while other disorders like Xeroderma pigmentosum tie to DNA repair defects. This guide reveals the correct matching from the MCQ and breaks down all options for exam success in genetics and molecular biology.

Correct Answer

The right match is (C) P-3; Q-1; R-4; S-2. Sickle-cell anemia (P) stems from a point mutation in the β-globin gene, causing hemoglobin S formation. Xeroderma pigmentosum (Q) arises from nucleotide excision repair mutations, impairing UV damage fix. Tay-Sachs disease (R) results from hexosaminidase A gene defects, leading to GM2 ganglioside buildup. Down syndrome (S) involves trisomy 21, an extra chromosome copy.

Why Option C Works

Column I pairs perfectly with Column II in C: P-3 (β-globin mutation defines sickle-cell as the first molecular disease). Q-1 matches xeroderma’s repair pathway failure, causing skin cancer risk. R-4 fits Tay-Sachs enzyme loss in lysosomal storage. S-2 aligns with Down syndrome’s chromosomal nondisjunction.

Option Analysis

• (A) P-1; Q-4; R-2; S-3: Wrong—P links to excision repair (Q’s trait), not sickle-cell; S-3 mismatches trisomy with globin defect.

• (B) P-3; Q-4; R-1; S-2: Close but fails on Q (hexosaminidase suits R) and R (repair fits Q, not Tay-Sachs).

• (C) P-3; Q-1; R-4; S-2: Correct, as detailed above with precise molecular ties.

• (D) P-4; Q-2; R-3; S-1: Incorrect—P-4 assigns Tay-Sachs enzyme to anemia; Q-2 wrongly ties trisomy to pigmentosum.

Exam Tips

Focus on molecular hallmarks: point mutations for sickle-cell and Tay-Sachs, chromosomal for Down, repair defects for xeroderma. Practice match-ups to master NEET/GATE biotech questions.