A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 2720-g (6-lb) female newborn is delivered at term to a 39-year-old woman, gravida 3, para 2. Examination in the delivery room shows micrognathia, prominent occiput with flattened nasal bridge, and pointy low-set ears. The eyes are upward slanting with small palpebral fissures. The fists are clenched with fingers tightly flexed. The index finger overlaps the third finger and the fifth finger overlaps the fourth. A 3/6 holosystolic murmur is heard at the lower left sternal border. The nipples are widely spaced and the feet have prominent heels and convex, rounded soles. Which of the following is the most likely cause of these findings?
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A
Trisomy 18Correct. clenched fists with overlapping digits, rocker-bottom feet, micrognathia, low-set malformed ears, and VSD are pathognomonic for trisomy 18.
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B
Fetal alcohol syndromeIncorrect. FAS shows smooth philtrum, thin vermilion border, small palpebral fissures, and growth restriction — not the overlapping fingers and rocker-bottom feet.
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C
Deletion of Chromosome 5pIncorrect. Cri-du-chat (5p-) features a high-pitched cry and microcephaly without the overlapping-finger / rocker-bottom-foot combination.
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D
Trisomy 13Incorrect. Trisomy 13 features holoprosencephaly, cleft lip/palate, polydactyly, and microphthalmia — not the overlapping-finger pattern.
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E
Trisomy 21Incorrect. Down syndrome features upslanting palpebral fissures, single palmar crease, brushfield spots, and AV-septal defects — not clenched overlapping fingers and rocker-bottom feet.
↑ Tap an answer to reveal the reasoning
Answer: A. A newborn with micrognathia, prominent occiput, low-set malformed ears, clenched fists with overlapping fingers (index over third, fifth over fourth), rocker-bottom feet, widely spaced nipples, and a holosystolic murmur (likely VSD) is the textbook picture of trisomy 18 (Edwards syndrome). Maternal age >35 is a risk factor.
Edwards syndrome is the second most common autosomal trisomy after Down syndrome, but has a much worse prognosis: most affected newborns die within the first year of life from congenital heart disease, apnea, or feeding difficulty. Characteristic findings include intrauterine growth restriction, microcephaly, congenital heart defects (especially VSD), horseshoe kidney, omphalocele, and the distinctive clenched-fist posture with overlapping digits.
Distinguishing distractors: trisomy 13 (Patau) features holoprosencephaly, cleft lip/palate, polydactyly, microphthalmia, and cutis aplasia. Cri-du-chat (5p deletion) presents with high-pitched cat-like cry, microcephaly, and intellectual disability — without the overlapping-finger / rocker-bottom-foot combination. Fetal alcohol syndrome features smooth philtrum, thin upper lip, small palpebral fissures, and growth restriction but not the skeletal/digit anomalies described.
Key pearl: clenched fists with overlapping fingers + rocker-bottom feet + micrognathia + low-set ears = trisomy 18.
**Why each option:**
**A.** Correct — clenched fists with overlapping digits, rocker-bottom feet, micrognathia, low-set malformed ears, and VSD are pathognomonic for trisomy 18.
**B.** FAS shows smooth philtrum, thin vermilion border, small palpebral fissures, and growth restriction — not the overlapping fingers and rocker-bottom feet.
**C.** Cri-du-chat (5p-) features a high-pitched cry and microcephaly without the overlapping-finger / rocker-bottom-foot combination.
**D.** Trisomy 13 features holoprosencephaly, cleft lip/palate, polydactyly, and microphthalmia — not the overlapping-finger pattern.