The enzyme deficient in Galactosemia is:-

Most Common Galactosemia is Galactose 1- phosphate uridyl transferase (GALT) deficiency Galactose (Diet- from milk/milk products) | Galactokinase Galactose - 1- Phosphate | GALT UDP - Galactose | Epimerase UDP- Glucose Deficiency of any of the enzyme in galactose metabolism will lead to galactosemia Galactokinase deficiency: Minor type galactosemia Substrate galactose gets accumulated Galactose later gets reduced to Galactitol which causes Oil Drop Cataract GALT (Galactose - 1 - phosphate Uridyl transferase) deficiency: More common Leads to Classical type galactosemia Substrate galactose - 1 - phosphate gets accumulated in Liver and Brain | Leading to | Jaundice Hepatomegaly Mental retardation Oil drop cataract also occurs here because galactose-1-phosphate when gets accumulated inhibits galactokinase which leads to galactose accumulation Sphingomyelinase, Hexosaminidase and Glucocerebrosidase are all deficient in Sphingolipidoses