Homocystinuria, also known as Cystathionine beta synthase deficiency, is an inherited disorder of the metabolism of the amino acidmethionine, often involving cystathionine beta synthase. It is an inherited autosomal recessive trait, which means a child needs to inherit the defective gene from both parents to be affected.
This defect leads to a multisystemic disorder of the connective tissue, muscles, CNS, and cardiovascular system. Homocystinuria represents a group of hereditary metabolic disorders characterized by an accumulation of homocysteine in the serum and an increased excretion of homocysteine in the urine. Infants appear to be normal and early symptoms, if any are present, are vague.
A family history of homocystinuria
Flush across the cheeks
Tall, thin build
High-arched feet (pes cavus)
Knock-knees (genu valgum)
90% have ectopia lentis
extensive atheroma formation at young age which affects many arteries but not the coronary arteries
The life expectancy of patients with homocystinuria is reduced only if untreated. It is known that before the age of 30, almost one fourth of patients die as a result of thrombotic complications (e.g. heart attack).
No specific cure has been discovered for homocystinuria; however, many people are treated using high doses of vitamin B6 (also known as pyridoxine). Slightly less than 50% respond to this treatment and need to intake supplemental vitamin B6 for the rest of their lives. Those who do not respond require a low methionine diet, and most will need treatment with trimethylglycine. A normal dose of folic acid supplement and occasionally added cysteine in the diet is helpful.
Low-protein food is recommended for this disorder requires food products which are low in particular types of amino-acid (i.e. methonine).