Galactosemia II (GALK),Disease,Galactokinase deficiency or Galactosemia type II is caused by mutation in the GALK1 gene on chromosome 17q24. Galactokinase deficiency is an autosomal recessive disorder which causes cataract formation in children not maintained on a lactose-free diet. Cataract formation is the result of osmotic phenomena caused by the accumulation of galactitol in the lens.