Mutated Residue Biochemical Effect Clinical Manifestation V94M, K257R, L313M, R335H Strongly impaired turnover number and specificity constant Severe generalized galactosemia.[3] S81R, T150M, P293L Mild turnover number impairment Intermediate galactosemia.[6] L183P, D103G, G90E, N34S Strongly impaired turnover number and specificity constant; increased proteolytic digestion. Severe generalized galactosemia.[3]