Galactosemia is caused by a deficiency in which enzyme?

Galactosemia is an inherited metabolic disorder characterized by the inability to properly metabolize galactose due to enzyme deficiencies. The correct choice identifies galactose-1-phosphate uridine diphosphate transferase (Gal-1-PUT) as the key enzyme affected in classic galactosemia. This enzyme plays a crucial role in the conversion of galactose-1-phosphate to glucose-1-phosphate, facilitating the metabolism of galactose, which is a sugar found in milk and dairy products.

When there is a deficiency in Gal-1-PUT, galactose and its metabolites accumulate in the body, leading to serious complications such as liver damage, intellectual disability, and cataracts, if left untreated. The management of galactosemia involves dietary restriction of galactose, particularly from sources like milk.

Other potential enzymes listed do not relate to the condition in question. For example, fructose-1,6-bisphosphatase plays a role in gluconeogenesis, glucose-6-phosphatase is crucial for glucose production in the liver, and galactokinase is involved in the phosphorylation of galactose but is not responsible for the broader spectrum of galactose metabolism