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Rett Syndrome — MRCPsych Paper B MCQ

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HardChild & Adolescent PsychiatryRett SyndromeMRCPsych Paper B

A 5-year-old girl is assessed following developmental regression. Her development appeared typical during the first year of life. From 18 months, she lost purposeful hand use and acquired words, and her head growth decelerated. She now has repetitive midline hand-to-mouth and hand-washing movements, episodic breath-holding while awake, and an apraxic gait. After initial social withdrawal, her eye contact and social interest have partly improved, although language and purposeful hand function remain severely impaired. Which diagnosis best accounts for this presentation?

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Correct answer: C — Rett syndrome

The diagnosis is Rett syndrome. The discriminating pattern is apparently typical early development followed by regression in acquired language and purposeful hand use, with characteristic midline hand stereotypies, gait apraxia, decelerating head growth and awake breathing abnormalities. Partial recovery of social interest after an initially autism-like regressive phase is also characteristic. Autism spectrum disorder may involve language or social regression but does not adequately explain this neurological pattern. Childhood disintegrative disorder historically required at least 2 years of apparently normal development and lacks the characteristic Rett motor phenotype. Landau-Kleffner syndrome primarily causes acquired epileptic aphasia, usually with epileptiform EEG abnormalities, rather than loss of purposeful hand use. Fragile X syndrome usually produces developmental delay rather than this distinctive regression and predominantly affects boys more severely.

Reference: NHS. Rett syndrome: Signs and symptoms, causes and diagnosis. Last reviewed 17 March 2023. https://www.nhs.uk/conditions/rett-syndrome/