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Unexplained developmental delay — RACP Paediatrics MCQ

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ModerateGeneticsUnexplained developmental delayRACP Paediatrics

A 2-year-old presents with global developmental delay, hypotonia, and dysmorphic features that do not fit a recognisable syndrome. Karyotype is normal. What is the most appropriate next genetic investigation?

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Correct answer: D — Chromosomal microarray (CMA)

Chromosomal microarray (CMA) is the recommended first-tier genetic investigation for unexplained developmental delay/intellectual disability with or without dysmorphic features. It detects submicroscopic copy number variants (deletions and duplications) that are not visible on standard karyotype. Diagnostic yield is approximately 15-20%.

Reference: RACP Paediatric Curriculum – Genetics; RCH Melbourne – 2023 – Developmental Delay CPG