FDR Schizophrenia Risk — MRCPsych Paper B MCQ

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EasySchizophrenia & PsychosisFDR Schizophrenia RiskMRCPsych Paper B

Across first-degree relatives of an individual with schizophrenia, where there is one affected relative, what is the commonly quoted approximate lifetime risk of developing schizophrenia?

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Correct answer: E — 10%

The best answer is E: approximately 10%. A first-degree relative—parent, full sibling or offspring—of a person with schizophrenia has a substantially increased lifetime risk, commonly quoted as about 10%, although estimates vary by the precise relationship and study population. UK public-health data give a range of approximately 6–17%. The 1% option approximates population lifetime risk rather than risk in a first-degree relative. Risks of 20% or 30% are too high for the average relative of a single affected person. A risk near 50% is associated with concordance in monozygotic twins, not first-degree relatives generally, and also demonstrates that genetic vulnerability is not deterministic.

Reference: Public Health England. Psychosis Data Report, section on predisposing factors, 2019. https://assets.publishing.service.gov.uk/media/5c5176ff40f0b6254b1b101e/Psychosis_data_report.pdf