DNA Repair Disorders

⏱️ 30 mins read 📖 Genetics 🎯 MLA Relevance: High

DNA repair disorders are inherited conditions in which defective DNA repair predisposes to cancer, neurodegeneration and immunodeficiency.

📌 Learning Objectives

Describe the underlying mechanism of DNA Repair Disorders.
Identify the key clinical features and complications of DNA Repair Disorders.
Outline the appropriate investigations and management of DNA Repair Disorders.
Discuss the implications for patients and families of DNA Repair Disorders.

📋 Overview

Examples include xeroderma pigmentosum (nucleotide excision repair), ataxia telangiectasia (ATM gene, double-strand break repair), Fanconi anaemia (DNA crosslink repair), and Lynch syndrome (mismatch repair).

🔬 Basic Science

🏥 Clinical Relevance

Synthetic lethality (e.g. PARP inhibitors in BRCA-mutant cancers) exploits DNA repair defects therapeutically.

🧪 Investigations

Investigation depends on clinical context: relevant blood tests, imaging, and specific genetic or histopathological tests as appropriate. Refer to specialist services where indicated.

💊 Management

Management is condition-specific and typically multidisciplinary, combining medical therapy, surgical intervention where appropriate, supportive care, and family/genetic counselling.

Revision Resources – expand the sections below for high-yield notes, exam pearls, key facts and further reading.

🎯 MLA High-Yield Notes & Quick Revision ⌄

Common SBA themes: recognising the underlying mechanism, identifying classic clinical features, and choosing the first-line investigation or management step. Watch for inheritance pattern and characteristic associations.

dna repair xeroderma pigmentosum ataxia telangiectasia fanconi mmr

Xeroderma pigmentosum is due to defective nucleotide excision repair and causes UV-induced skin cancers.
Ataxia telangiectasia involves ATM mutations and impaired DSB repair.
Fanconi anaemia: defective DNA crosslink repair and bone marrow failure.
Lynch syndrome involves mismatch repair gene mutations.
PARP inhibitors exploit synthetic lethality in BRCA-mutant cancers.

⭐ Exam Pearls ⌄

⭐ High Yield

Xeroderma pigmentosum is due to defective nucleotide excision repair and causes UV-induced skin cancers.

Ataxia telangiectasia involves ATM mutations and impaired DSB repair.

Fanconi anaemia: defective DNA crosslink repair and bone marrow failure.

Lynch syndrome involves mismatch repair gene mutations.

PARP inhibitors exploit synthetic lethality in BRCA-mutant cancers.

💡 Clinical Pearl

Dna Repair: Synthetic lethality (e.g. PARP inhibitors in BRCA-mutant cancers) exploits DNA repair defects therapeutically.

⚠️ Exam Tip — Common Mistakes

Confusing the mechanism of DNA Repair Disorders with related conditions.

Missing classic clinical features of DNA Repair Disorders in SBA stems.

Failing to consider DNA Repair Disorders in the differential diagnosis.

🔑 Key Facts ⌄

Xeroderma pigmentosum is due to defective nucleotide excision repair and causes UV-induced skin cancers.

Ataxia telangiectasia involves ATM mutations and impaired DSB repair.

Fanconi anaemia: defective DNA crosslink repair and bone marrow failure.

Lynch syndrome involves mismatch repair gene mutations.

PARP inhibitors exploit synthetic lethality in BRCA-mutant cancers.

🔗 Related Topics ⌄

📚 References ⌄

GMC MLA Content Map
NICE Clinical Knowledge Summaries
BMJ Best Practice

Further Resources

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