Galactokinase deficiency is an uncommon, hereditary condition characterized by a lack of galactokinase, an enzyme that plays a vital role in breaking down galactose. Galactose is a simple sugar that originates from lactose, the sugar found in milk. This deficiency is a type of genetic disorder that follows an autosomal recessive pattern. The disorder results in a form of galactosaemia, which is the body’s inability to transform galactose into glucose, another simple sugar. The only evident symptom of galactokinase deficiency galactosaemia is the formation of cataracts, which usually become noticeable in affected infants within their first few weeks of life.