Q.16 Which one of the following is NOT a therapeutic agent based on nucleic acid for the treatment of
genetic disorders?
(A) Antisense oligonucleotide (B) Ribozyme
(C) Aptamer (D) Avidin
Answer: (D) Avidin
Avidin stands out as the option not based on nucleic acids, unlike the others which are directly derived from DNA or RNA structures for therapeutic use in genetic disorders. Antisense oligonucleotides, ribozymes, and aptamers function through sequence-specific nucleic acid interactions to modulate gene expression or protein activity.
Option Breakdown
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Antisense Oligonucleotide (A): Short single-stranded DNA or RNA analogs that bind complementary mRNA via base-pairing, blocking translation or inducing degradation to correct aberrant gene expression in disorders like spinal muscular atrophy.
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Ribozyme (B): Catalytic RNA molecules that cleave specific mRNA targets, offering enzyme-like activity for precise RNA interference in genetic diseases such as cystic fibrosis.
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Aptamer (C): Single-stranded nucleic acids folded into 3D structures that bind proteins or small molecules with high affinity, used therapeutically like pegaptanib for inhibiting vascular endothelial growth factor in eye disorders.
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Avidin (D): A tetrameric protein from egg whites that binds biotin tightly; it aids drug delivery or reversal of anticoagulants but is purely protein-based, not nucleic acid-derived.
Nucleic acid-based therapeutic agents for genetic disorders revolutionize treatment by targeting faulty genes at the molecular level. From antisense oligonucleotides to ribozymes and aptamers, these RNA or DNA-derived tools correct genetic defects precisely. However, not all agents fit this category—avidin, a protein, does not qualify as a nucleic acid-based therapeutic agent for genetic disorders.
Core Concepts
Nucleic acid therapeutics harness DNA or RNA’s specificity for gene silencing, editing, or protein modulation in conditions like Duchenne muscular dystrophy or Huntington’s disease.
Detailed Option Analysis
| Option | Type | Mechanism | Genetic Disorder Application | Nucleic Acid-Based? |
|---|---|---|---|---|
| Antisense Oligonucleotide | Synthetic DNA/RNA analog | mRNA binding/degradation | Spinal muscular atrophy, ALS | Yes |
| Ribozyme | Catalytic RNA | Site-specific RNA cleavage | Cystic fibrosis trials | Yes |
| Aptamer | ssDNA/ssRNA ligand | High-affinity protein binding | AMD (pegaptanib approved) | Yes |
| Avidin | Protein (biotin binder) | Drug delivery/targeting aid | None directly; supports gene therapy vectors | No |
Why Avidin Fails the Criteria
Avidin excels in biotin-avidin systems for targeted delivery, such as pretargeting in cancer gene therapy or reversing biotinylated drugs. Yet, as a non-nucleic acid protein from avian sources, it lacks the sequence-specific binding of true nucleic acid therapeutics for genetic disorders. This distinction makes it the correct “NOT” choice in MCQs on biotech therapeutics.
