Galactose is a carbohydrate found in milk and is the primary source of carbohydrates in neonates, providing 40% of their energy. It is important for the formation of glucose-1-phosphate and galactosides. Deficiencies in galactose metabolism, such as galactose-1-phosphate uridyl transferase deficiency, can lead to serious health issues, including classical galactosaemia with symptoms like refusal to feed, jaundice, and organ failure. Biochemical abnormalities associated with classical galactosaemia include hypoglycaemia, hyperbilirubinaemia, liver enzyme abnormalities, and aminoaciduria.