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Trisomy 18 – Edwards — RACP Paediatrics MCQ

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ModerateGeneticsTrisomy 18 – EdwardsRACP Paediatrics

A newborn has rocker-bottom feet, overlapping fingers (index over third, fifth over fourth), micrognathia, prominent occiput, and a VSD. The infant is SGA. Karyotype confirms the diagnosis. What is the most likely chromosomal abnormality?

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Correct answer: C — Edwards syndrome (trisomy 18)

Rocker-bottom feet, overlapping fingers (2nd over 3rd, 5th over 4th – a characteristic hand posture), micrognathia, prominent occiput, SGA, and CHD (VSD, PDA, ASD) is trisomy 18 (Edwards syndrome). Median survival is 5-15 days. Some infants survive beyond infancy, particularly with cardiac surgery in selected cases.

Reference: RACP Paediatric Curriculum – Genetics; RCH Melbourne – 2023