Actually 3 different gene defects possible, most commonly Galactose-1-Phosphate uridyl transferase deficiency (GALT, or Gal-1-PUT). The others have different phenotypes.

Presents in the newborn period after initiation of milk feeding, most commonly with jaundice, which can be unconjugated in first week but becomes conjugated thereafter. The other features listed below are seen in only a minority:

• Vomiting,
• poor feeding
• Hypotonia
• Hepatomegaly
• Encephalopathy
• Cataract – can be present at birth, but more usually after a week or two.
• Sepsis – esp E coli septicaemia

Lab findings include hypoglycaemia, deranged LFTs, coagulopathy, metabolic acidosis, abnormal urine aminoacid excretion. Urine for reducing substances is not sensitive or specific. The definitive test is RBC Gal-1-PUT activity, but if a transfusion has been given alternatives are genotyping or testing the parents for carrier status.

Management is by diet. Nonetheless, neuropsych problems usually develop in adolescence and ovarian failure often occurs. Some debate about whether galactose can be tolerated from age 2-3yr.