A 9-year-old boy presents with progressive gait ataxia, loss of vibration sense, and retinitis pigmentosa. Peripheral smear shows spiky red cells (acanthocytes) and lipid profile shows absent plasma beta-lipoprotein. The neurological findings are attributable to deficiency of which vitamin?

• A Vitamin A
• B Vitamin D
• C Vitamin K
• D Vitamin E ✓

Explanation

Abetalipoproteinemia impairs assembly and secretion of chylomicrons and VLDL, so dietary fat-soluble vitamins cannot be absorbed and transported. Vitamin E is the principal antioxidant protecting membrane polyunsaturated fatty acids in neurons and erythrocytes; its deficiency produces a spinocerebellar syndrome mimicking Friedreich ataxia plus acanthocytosis. Vitamin A deficiency would cause visual impairment from retinol shortage, and vitamin K deficiency causes bleeding, neither of which explains progressive ataxia with acanthocytes.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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