A newborn baby refuses breast milk since the second day of birth, vomits on force-feeding but accepts glucose-water, develops diarrhea on third day, by fifth day she is jaundiced with liver enlargement and eyes show cataract. Urinary reducing sugar was positive but blood glucose estimated by glucose oxidation method was found low. The most likely cause is deficiency of:

**Core Concept**
The case describes a newborn baby presenting with symptoms of feeding refusal, vomiting, diarrhea, jaundice, liver enlargement, cataract, and positive urinary reducing sugar with low blood glucose. This constellation of symptoms is suggestive of a congenital metabolic disorder affecting glucose metabolism.

**Why the Correct Answer is Right**
The symptoms described are characteristic of Congenital Galactosemia, a genetic disorder caused by the deficiency of galactose-1-phosphate uridyltransferase (GALT) enzyme. This enzyme is crucial for the conversion of galactose to glucose in the liver. When galactose enters the body, it is converted to galactose-1-phosphate, which is then transferred to UDP-glucose by the GALT enzyme. Without this enzyme, galactose-1-phosphate accumulates, causing damage to the liver, kidneys, and eyes. The consumption of lactose-containing breast milk leads to the accumulation of galactose in the bloodstream, resulting in the symptoms described.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided in the question. Please ensure the question has all options before providing an explanation.

**Option B:** This option is not provided in the question. Please ensure the question has all options before providing an explanation.

**Option C:** This option is not provided in the question. Please ensure the question has all options before providing an explanation.

**Clinical Pearl / High-Yield Fact**
The key to diagnosing Congenital Galactosemia lies in the presence of a positive urinary reducing sugar test with low blood glucose levels despite the consumption of glucose-containing fluids. This unique combination of symptoms should prompt the clinician to suspect a congenital metabolic disorder affecting glucose metabolism.

**Correct Answer:** C. Galactosemia

✓ Correct Answer: A. Galactose 1-phosphate uridyl transferase