A 24-year-old woman taking high-dose isotretinoin for acne is found to be pregnant. Counseling should emphasize that the major concern is:

• A Neural tube defects due to folate antagonism
• B Skeletal fluorosis-like changes from bone mineral deposition
• C Fetal goiter from thyroid hormone displacement
• D Retinoic acid-mediated disruption of hindbrain and craniofacial development ✓

Explanation

Isotretinoin is 13-cis-retinoic acid, a vitamin A derivative. Excess retinoic acid alters Hox gene expression and causes a characteristic retinoid embryopathy with craniofacial, cardiac, thymic, and CNS abnormalities, particularly affecting hindbrain structures. It has no anti-folate action, so neural tube defect risk (option A) belongs to valproate, methotrexate, and antifolate drugs instead.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.