A neonate has hypotonia, flat facies, upward slanting palpebral fissures, and a single palmar crease. Echocardiography shows a common atrioventricular canal defect. Karyotype confirms 47,XX,+21. Which cardiac lesion is most characteristic of this chromosomal disorder?

• A Supravalvular aortic stenosis
• B Coarctation of the aorta
• C Truncus arteriosus
• D Atrioventricular septal defect ✓

Explanation

Endocardial cushion defects, including complete atrioventricular septal defect, are the most characteristic cardiac lesions in trisomy 21, followed by ventricular septal defect and ostium secundum atrial septal defect. Coarctation of the aorta points toward Turner syndrome, truncus arteriosus toward 22q11.2 deletion, and supravalvular aortic stenosis toward Williams syndrome, so these distractors are excluded by their syndromic associations.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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