How exactly is galactisemia a genetic disorder/mutation?

Galactosemia genetic: Galactosemia is a disease that affects how body processes a sugar called galactose which is present e.g. In dairy. It is an autosomal recessive condition which means that each parent is a carrier of a nonfunctional copy of a gene. Because their other copy of that gene is functional they don't have symptoms. If both parents pass on the nonfunctional copy to a child, the child will have galactosemia.

Dr Ali agreed