CMA for Developmental Delay — RACP Paediatrics MCQ

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ModerateNeurology & DevelopmentCMA for Developmental DelayRACP Paediatrics

A 4-year-old girl has global developmental delay. She has epicanthic folds, a flat nasal bridge, and upslanting palpebral fissures. Her karyotype is 46,XX. What genetic test may identify the cause?

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Correct answer: A — Chromosomal microarray (CMA)

Chromosomal microarray (CMA/SNP array) is the first-line genetic investigation for unexplained developmental delay/intellectual disability, detecting pathogenic copy number variants (deletions/duplications) in approximately 15-20% of cases. It has largely replaced karyotype as the first-tier test. If CMA is negative, whole exome/genome sequencing may be considered.

Reference: RACP – 2024 – Paediatric Curriculum: Clinical Genetics