Orphan Technologies is committed to reduce the burden of patients suffering from homocystinuria.

Please use this information and also see our Patient Resource page to learn more about assistance that is available.


is a disease that results from significantly elevated levels of the amino acid homocysteine which can result in debilitating effects in patients including severe cardiovascular, skeletal, neurologic and ophthalmologic complications.


Newborn screening testing for elevated methionine levels can capture can capture some classical HCY patients with significant biochemical CBS deficits. However, Patients are frequently diagnosed later in life with development delays in adolescence or with medical emergencies even later in life. It is not known what percentage of patients are never diagnosed and who may remain at risk for negative clinical events.


Classical homocystinuria is a rare genetic metabolic disorder caused by a deficiency in the enzyme cystathionine beta synthase (CBS). CBS is a pivotal enzyme in the conversion of the amino acid methionine to homocysteine and then to cysteine. Elevations in homocysteine are associated with an increased risk of severe cardiovascular, skeletal, ocular, neurocognitive effects.

Current HCU Treatment

The current treatment for patients with homocystinuria is a severely protein restricted diet supplemented with vitamin B6 therapy, betaine anhydrous powder, and medical foods. Compliance with the prescribed dietary restrictions and medical foods is extremely difficult, regularly resulting in inadequate metabolic control and lack of disease control.

Join Us and Make a Difference

Orphan Technologies has initiated a Natural History Study to learn more about homocystinuria patients, their challenges, and their outcomes. Find out more.