Homocystinuria (HCU) is an inherited metabolic disorder where the body has too much homocysteine. There are three main types of Homocystinuria that can cause this to happen, Cystathionine Beta Synthase, otherwise known as, Classical Homocystinuria, Cobalamin disorders and Severe MTHFR.
Classical Homocystinuria has two types, B6 responsive and non-B6 responsive. Those who are B6 responsive take B6 as their primary source of treatment, where those who are not B6 responsive may take B6, B12, Folic Acid, Betaine, Medical formula and follow a low protein diet.
There are many different types of HCU
Cobalamin C , Cobalamin D, Cobalamin E, Cobalamin F, Cobalamin G , Cobalamin, Cobalamin X, Cobalamin A
Patients with HCU inherit two defective copies of the gene from their parents. So each time their parents have a child they have a 1 in 4 chance of having a child with Homocystinuria.