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Autism spectrum disorder — MCCQE Part 1 MCQ

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HardDevelopmental DelayAutism spectrum disorderMCCQE Part 1

A 3-year-old has a multidisciplinary diagnosis of autism, global developmental delay, macrocephaly and dysmorphic features. Hearing testing is normal and there has been no seizure. Which etiologic investigation is most appropriate next?

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Correct answer: D — Arrange chromosomal microarray plus a phenotype-directed genetics review

Order contrast CT brain as the routine first etiologic investigation: Routine CT has low etiologic yield and exposes the child to radiation; neuroimaging is reserved for specific neurologic indications. Order EEG to screen for epileptiform activity in the absence of spells: EEG is indicated for suspected seizures or selected regression patterns, not as universal autism testing. Arrange chromosomal microarray plus a phenotype-directed genetics review: Genetics review can add Fragile X or syndrome-specific sequencing when clinical features support it and provides recurrence counselling. Repeat autism screening to determine whether genetic testing is warranted: Screening tools identify children needing diagnostic assessment but do not establish a genetic cause. Defer etiologic investigation until the child begins formal schooling: Delay loses opportunities for counselling, anticipatory care and condition-specific surveillance.

Reference: https://cps.ca/en/documents/position/asd-diagnostic-assessment