Contents
Rare inborn error of metabolism due to impaired degradation of galactose.
- Autosomal recessive inheritance
- D/t galactose-1-phosphate uridyltransferase (GALT/GALPUT) deficiency
Pathophysiology
Three different enzymes are involved in the metabolism of galactose include galactose-1-phosphate uridyltransferase (GALT), galactokinase, and epimerase.
Galactosemia is caused by deficient activity of GALT, the second enzyme of the Leloir pathway.
- Increased galactose-1-phosphate accumulates in the liver, kidney, brain, tongue, lens, and cutaneous fibroblasts, and causes injury. In many patients
- Rapid symptom regression occurs with early initiation of treatment, but outcomes that affect life negatively in the short and long term may be observed
Clinical features
These present following intake of galactose in the neonatal period:
- Hepatocellular damage: Jaundice (M/C, 86% cases), hepatosplenomegaly, hepatic failure
- Feeding difficulties
- Failure to thrive
- Hypoglycemia
- Renal tubular dysfunction
- Muscular hypotonia
- Oil drop cataracts (accumulation of galactriol in lens)
- E coli sepsis in untreated infants
Diagnosis
Urinary sugar tests:
- Benedict’s test (+): Reducing sugar present
- Mucic acid test (+): Galactose specific test
Enzyme assays:
- ↑ Erythrocyte galactose-1-phosphate
- ↓ Erythrocyte galactose-1-phosphate uridylyltranserase (GALT) enzyme activity
Management
Lactose-restricted diet followed by long-term diet therapy:
First ten days of life, the severe acute neonatal complications are usually prevented
- Breastmilk, cow’s milk, and formulas contain a significant amount of lactose thus galactose; therefore, they should not be given to these patients.
- In infancy, formulas containing lactose-free casein hydrolysates or separated oligosaccharides can be used.
Exogenous calcium and vitamin D supplementation:
Prevent reduction in bone mineralization in patients with galactosemia