Question:
A 2-week-old baby presented with vomiting, acidosis and early cataract. Which of the following enzyme is defective?
A 2-week-old baby presented with vomiting, acidosis and early cataract. Which of the following enzyme is defective?
Show Hint
Vomiting + acidosis + hepatic illness + cataract in a milk-fed neonate = the severe (classic) form, not the cataract-only galactokinase form.
Updated On: Aug 27, 2026
- Galactose 1 Po4 uridyl transferase
- Galactokinase
- Hexokinase
- Aldol reductase
Show Solution
Verified By Collegedunia
The Correct Option is A
Solution and Explanation
Step 1: Read the clinical picture. A neonate (about 2 weeks old) with vomiting, metabolic acidosis, failure to thrive and cataract after starting milk is the classic presentation of classic galactosemia. Other features include hepatomegaly, jaundice, hypoglycaemia and a predisposition to E. coli sepsis.
Step 2: Recall the metabolic block. Classic galactosemia is caused by deficiency of galactose-1-phosphate uridyltransferase (GALT). This enzyme normally converts galactose-1-phosphate (with UDP-glucose) into UDP-galactose. Its deficiency causes galactose-1-phosphate to accumulate, which is toxic to the liver, kidney and brain, producing the severe systemic illness.
Step 3: Explain the cataract. Excess galactose is shunted by aldose reductase to galactitol, which accumulates in the lens, draws in water osmotically and causes early (oil-droplet) cataract. The systemic features (vomiting, acidosis, hepatic involvement) come from the toxic galactose-1-phosphate, which is why the severe form is GALT (transferase) deficiency.
Step 4: Exclude the distractors. Galactokinase deficiency causes a milder disease - isolated cataracts only (from galactitol), WITHOUT vomiting, acidosis or hepatic/renal damage - so B does not fit a baby with systemic illness. Hexokinase phosphorylates glucose in glycolysis and is unrelated to this presentation; C is wrong. Aldose reductase (the option's 'aldol reductase') actually PRODUCES galactitol that causes the cataract - it is not deficient; its deficiency would protect against cataract, so D is wrong.
Final answer: Option A - Galactose-1-phosphate uridyltransferase.
Step 2: Recall the metabolic block. Classic galactosemia is caused by deficiency of galactose-1-phosphate uridyltransferase (GALT). This enzyme normally converts galactose-1-phosphate (with UDP-glucose) into UDP-galactose. Its deficiency causes galactose-1-phosphate to accumulate, which is toxic to the liver, kidney and brain, producing the severe systemic illness.
Step 3: Explain the cataract. Excess galactose is shunted by aldose reductase to galactitol, which accumulates in the lens, draws in water osmotically and causes early (oil-droplet) cataract. The systemic features (vomiting, acidosis, hepatic involvement) come from the toxic galactose-1-phosphate, which is why the severe form is GALT (transferase) deficiency.
Step 4: Exclude the distractors. Galactokinase deficiency causes a milder disease - isolated cataracts only (from galactitol), WITHOUT vomiting, acidosis or hepatic/renal damage - so B does not fit a baby with systemic illness. Hexokinase phosphorylates glucose in glycolysis and is unrelated to this presentation; C is wrong. Aldose reductase (the option's 'aldol reductase') actually PRODUCES galactitol that causes the cataract - it is not deficient; its deficiency would protect against cataract, so D is wrong.
Final answer: Option A - Galactose-1-phosphate uridyltransferase.
Was this answer helpful?
0
0
Top NEET PG Biochemistry Questions
- Which of the following clotting factors is needed for gamma-glutamyl carboxylase?
- A patient presented with diarrhea, dermatitis, and dementia. Which of the following vitamin deficiencies would you suspect in this patient?
- A young boy presents to the OPD with hypoglycemia and muscle cramps, on exertion or while playing. Then he becomes normal after resting for a while. These episodes are recurrent after a period of activity. He has decreased serum lactate and glucose levels. Which of the following diseases is he most likely to be suffering from?
- A family consumes only polished rice. Which of the following combinations of vitamin deficiency and enzymatic defect will be present in this family?
- A chronic alcoholic patient presented to the casualty with confusion, ataxia, and painful eye movements. What could be the vitamin deficiency seen in this patient?
View More Questions
Top NEET PG Questions
- A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3 days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000 cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting time was normal. What is the most likely diagnosis?
- Which of the following statements is true about Trichomonas vaginalis?
- A lady from West Rajasthan presented with an ulcer surrounded by erythema on the right leg. Microscopy of the biopsy from the edge of the ulcer showed organisms with dark staining nuclei and kinetoplast. What is the most likely causative agent?
- A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
- Infection with Clonorchis sinensis is associated with an increased risk of__?
View More Questions