An infant fed predominantly on goat milk presents with macrocytic anemia. Bone marrow shows megaloblastic changes. Neurological examination is completely normal. Which of the following BEST explains the absence of neurological findings?
- A Goat milk contains adequate cobalamin but lacks folate
- B The infant is too young to manifest neurological deficits
- C Folate deficiency does not impair myelin synthesis unlike cobalamin deficiency ✓
- D Goat milk folate protects the nervous system selectively
Correct answer: C. Folate deficiency does not impair myelin synthesis unlike cobalamin deficiency
Explanation
Goat milk is notoriously deficient in folate, producing megaloblastic anemia in infants. Unlike cobalamin deficiency, folate deficiency does not cause subacute combined degeneration because methylmalonyl-CoA mutase activity depends on cobalamin, not folate, and impaired myelin synthesis in C12 deficiency stems partly from accumulated methylmalonic acid. Hence pure folate deficiency gives megaloblastic anemia with a normal neurological examination.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.