Question:medium
Which of the following is associated with a defect in mismatch repair?
Which of the following is associated with a defect in mismatch repair?
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Think about which DNA repair pathway corrects base mismatches introduced during DNA replication.
Updated On: Jun 23, 2026
- Hereditary NPCC
- SCID
- Bloom Disorder
- MUTYH Associated Polyposis
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The Correct Option is A
Solution and Explanation
DNA repair mechanisms and their associated genetic diseases:
| Repair Type | DNA Damage | Disease |
|---|---|---|
| NHEJ | Double-strand breaks | SCID, RS-SCID |
| Homologous Recombination | Double-strand breaks | Werner Syndrome |
| Nucleotide Excision Repair | Pyrimidine dimers, bulky adducts | Xeroderma Pigmentosa, Cockayne Syndrome |
| Base Excision Repair | Abasic sites | MUTYH-associated Polyposis |
| Mismatch Repair (MMR) | Base mismatches | HNPCC / Lynch Syndrome |
Mismatch repair involves MLH1, MSH2, MSH6, and PMS2 genes. Mutations in these lead to microsatellite instability (MSI), a hallmark of Lynch syndrome / HNPCC.
Key distinction: MUTYH-associated Polyposis involves Base Excision Repair -- not mismatch repair. SCID involves NHEJ. These are common distractors.
\[\boxed{\text{Hereditary NPCC (Lynch Syndrome)}}\]
| Repair Type | DNA Damage | Disease |
|---|---|---|
| NHEJ | Double-strand breaks | SCID, RS-SCID |
| Homologous Recombination | Double-strand breaks | Werner Syndrome |
| Nucleotide Excision Repair | Pyrimidine dimers, bulky adducts | Xeroderma Pigmentosa, Cockayne Syndrome |
| Base Excision Repair | Abasic sites | MUTYH-associated Polyposis |
| Mismatch Repair (MMR) | Base mismatches | HNPCC / Lynch Syndrome |
Mismatch repair involves MLH1, MSH2, MSH6, and PMS2 genes. Mutations in these lead to microsatellite instability (MSI), a hallmark of Lynch syndrome / HNPCC.
Key distinction: MUTYH-associated Polyposis involves Base Excision Repair -- not mismatch repair. SCID involves NHEJ. These are common distractors.
\[\boxed{\text{Hereditary NPCC (Lynch Syndrome)}}\]
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