An infant diagnosed with classic galactosemia was started on strict dietary galactose restriction and improved. However, complete elimination of dietary galactose is not recommended in the long term because the patient cannot synthesize which metabolite endogenously, making small amounts of galactose necessary?

• A UDP-glucuronate
• B UDP-galactose required for glycoprotein and glycolipid synthesis ✓
• C Galactonate required for collagen cross-linking
• D N-acetylgalactosamine required for ABO antigen synthesis

Explanation

UDP-galactose is needed for synthesis of glycoproteins, glycolipids, and lactose, including compounds such as ceramide galactoside in myelin. In classical galactosemia (galactose-1-phosphate uridyltransferase deficiency), the only route to UDP-galactose is the Leloir pathway using dietary galactose, so complete avoidance risks impaired synthesis of these structural molecules. Small quantities of galactose-containing foods are therefore allowed later in life.

Reference: Nelson Textbook of Pediatrics, 22nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.