The way someone gets galactosemia is through a gene mutation.
Inheriting galactosemia from both parents is how you get galactosemia.
Galactosemia is an inherited metabolic disorder that is caused by mutations in the genes which encode enzymes that are involved in the breakdown of galactose, which is a sugar that is found in dairy products and milk.
Classic galactosemia type I is caused by mutations in the GALT gene, that codes for the enzyme galactose-1-phosphate uridyl transferase (GALT).
Galactokinase deficiency type II is caused by mutations in the GALK1 gene, that codes for the enzyme galactokinase.
And Galactose epimerase deficiency type III is caused by mutations in the GALE gene, that codes for the enzyme galactose epimerase.
And when these enzymes are deficient, galactose accumulates in your body and results in various different health issues such as intellectual disability, growth failure, cataracts, kidney failure and even liver damage.
Galactosemia is inherited in an autosomal recessive pattern, which means that the child has to inherit a mutated gene from both parents to develop the galactosemia condition.