In galactosemia (classical, GALT deficiency), galactose-1-phosphate accumulates. The MOST dangerous acute complication and the biochemical explanation for cataracts in untreated patients are:

• A Acute: hemolytic anemia from galactose oxidation; cataracts from galactose-1-phosphate lens deposits
• B Acute: E. coli sepsis due to immune deficiency; cataracts from galactitol accumulation via aldose reductase in lens
• C Acute: hypoglycemia due to galactose-1-phosphate inhibiting phosphoglucomutase; cataracts from galactitol ✓
• D Acute: hyperammonemia; cataracts from direct lens galactose toxicity

Explanation

GALT deficiency allows galactose-1-phosphate accumulation. Galactose-1-phosphate inhibits phosphoglucomutase (blocking glycogenolysis) and GALT itself, causing severe hypoglycemia after milk feeds. Neonates show jaundice, hepatomegaly, coagulopathy, and E. coli neonatal sepsis (mechanism unclear — possibly immune dysfunction). For cataracts: lens epithelial cells lack GALT but have aldose reductase; galactose is reduced to galactitol (a sugar alcohol), which cannot exit the lens and accumulates, drawing water osmotically, causing lens opacification ("oil droplet" cataract). Galactitol also damages nerve cells.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.