What is the cause of galactosemia I?

Answer:
Caused by defects in both copies of the gene that codes for an enzyme called galactose-1-phosphate uridyl transferase (GALT). There are 30 known different mutations in this gene that cause GALT to malfunction.
First answer by Gale Ency. of Medicine. Last edit by Gale Ency. of Medicine. Contributor trust: 37 [recommend contributor recommended]. Question popularity: 23 [recommend question].