Classic galactosemia vs Galactokinase deficiency
How to tell Classic galactosemia and Galactokinase deficiency apart when a board question makes them look alike.
Classic galactosemia is sick infant with liver disease and E coli sepsis; galactokinase deficiency is mainly cataracts.
Side by side
Classic galactosemia causes jaundice, hepatomegaly, vomiting, failure to thrive, cataracts, and E coli sepsis after milk ingestion from GALT deficiency.
Galactokinase deficiency causes infant cataracts from galactitol accumulation but usually lacks severe liver disease and E coli sepsis.
GALT deficiency accumulates galactose-1-phosphate, injuring liver, kidney, brain, and lens.
Galactokinase deficiency shunts galactose toward galactitol in the lens, producing isolated cataracts.
Reducing substance in urine, liver dysfunction, hypoglycemia, and E coli sepsis after milk support classic galactosemia.
Cataracts with relatively mild systemic illness support galactokinase deficiency.
The trap
Both can cause cataracts after milk exposure, but systemic toxicity separates GALT deficiency.
The repair move
For galactose disorders, decide whether cataracts are isolated or part of severe systemic liver/sepsis disease.
Try a free question
CoreA 1-week-old neonate develops vomiting, jaundice, hepatomegaly, and lethargy after starting breastfeeding. Blood culture grows Escherichia coli. Urine is positive for reducing substances but negative for glucose on dipstick. Which enzyme is deficient?
Show answer and explanation
Answer: A. Galactose-1-phosphate uridyltransferase. Classic galactosemia is GALT deficiency; galactose-1-phosphate accumulates and injures liver, kidney, and brain. Affected neonates are at high risk of E. coli sepsis. Treatment is removal of galactose/lactose from diet.
Why the other choices are tempting
- B. Galactokinase deficiency causes mainly infantile cataracts WITHOUT severe liver disease or E. coli sepsis.
- C. Aldolase B deficiency (hereditary fructose intolerance) presents after fructose exposure, not milk exposure.
- D. Fructokinase deficiency (essential fructosuria) is benign and asymptomatic.
- E. Glucose-6-phosphatase deficiency (Von Gierke) causes fasting hypoglycemia, not milk-triggered illness with E. coli sepsis.
Flashcards
Tap a card to flip it.
What clue supports Classic galactosemia?
Choose Classic galactosemia when the stem gives this pattern: Classic galactosemia causes jaundice, hepatomegaly, vomiting, failure to thrive, cataracts, and E coli sepsis after milk ingestion from GALT deficiency.
What clue supports Galactokinase deficiency?
Choose Galactokinase deficiency when the stem gives this contrasting pattern: Galactokinase deficiency causes infant cataracts from galactitol accumulation but usually lacks severe liver disease and E coli sepsis.
Quick answers
What is the fastest way to tell Classic galactosemia from Galactokinase deficiency?
Classic galactosemia is sick infant with liver disease and E coli sepsis; galactokinase deficiency is mainly cataracts.
What is the key clue for Classic galactosemia?
Classic galactosemia causes jaundice, hepatomegaly, vomiting, failure to thrive, cataracts, and E coli sepsis after milk ingestion from GALT deficiency.
What is the key clue for Galactokinase deficiency?
Galactokinase deficiency causes infant cataracts from galactitol accumulation but usually lacks severe liver disease and E coli sepsis.
What is the common trap with Classic galactosemia vs Galactokinase deficiency?
Both can cause cataracts after milk exposure, but systemic toxicity separates GALT deficiency.