Inborn errors of metabolism
An inherited problem with processing protein. A substance called homocysteine builds up in the blood. The lens of the eye can move out of place; the bones, blood vessels and brain can be affected.
Not part of the panel of Türkiye's National Newborn Screening Programme (heel-prick test). Source
Orphanet has a guideline for emergency doctors for this disease (language: French, Polish, German, English, Spanish, Italian). See on Orphanet
This page is translated from the Turkish original.
This disease is followed through the “Inborn errors of metabolism” group.
Methionine, one of the building blocks of proteins, cannot be fully broken down. The enzyme needed for this is missing. Homocysteine and methionine build up in the blood. The eyes, skeleton, blood vessels and brain can be affected.
Symptoms usually begin in childhood. In mild cases they may not be noticed until adulthood.
Homocysteine and methionine are measured in the blood or urine. The diagnosis is confirmed with a genetic test. In some countries it can be found through newborn screening, but some mild forms may be missed by screening.
About half of people respond well to a vitamin treatment. For those who do not respond, a special diet that restricts methionine and a special formula are used. If the diet starts in infancy, it can prevent problems. There is also an approved medicine that lowers homocysteine. Eye or bone surgery may be needed; special precautions against blood clots are taken before surgery. The doctor who follows the disease decides which treatment is suitable.
The disease is passed on through recessive inheritance. The mother and father are usually healthy carriers. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. When relatives marry, the chance that two carriers have children together is higher. Genetic counselling guides the family.
Source: MedlinePlus Genetics: Homocystinuria · NORD: Homocystinuria Due to Cystathionine Beta-Synthase Deficiency
These facts are taken from Orphanet and MedlinePlus records (last checked: October 7, 2026). Frequency values are approximate ranges.
Non-profit patient and family organizations in Türkiye working on this disease or disease group. Links are for information; Doktorclub is not affiliated with these organizations and does not endorse them.
For all rare diseases: Nadir Hastalıklar Federasyonu
Links checked on October 8, 2026.
Doktorclub does not diagnose, recommend treatments or refer you to hospitals or doctors. These pages are meant to help you talk with your doctor.
TürkiyeResearch and clinical trials
Istanbul University gave choline for 8 weeks to 15 patients whose homocysteine remained high despite treatment.
A clinical trial is a regulated study that tests whether a new treatment is safe and whether it works, in patients who volunteer. Most trials look for a certain age, genetic change and health condition. Taking part is voluntary.
Questions you can ask your doctor
ClinicalTrials.gov lists 4 active interventional studies for this disease. 2 are recruiting now; 2 have sites in Türkiye. Last checked: October 7, 2026.
Selected records (studies with a site in Türkiye first):
Late stage: the effect is being compared in a large group · Phase 3 · investigational (experimental)RecruitingSite in TürkiyeNCT06247085
Late stage: the effect is being compared in a large group · Phase 3 · investigational (experimental)Enrolling by invitationSite in TürkiyeNCT06431893
Middle stage: the effect is being tested in a small group · Phase 1 / Phase 2 · investigational (experimental)RecruitingNCT03406611
Non-drug study (device, procedure, care, etc.)Active, not recruitingNCT06495567
See all studies on ClinicalTrials.gov · Joining clinical trials
EUNew treatments and approvals
In Europe, leriglitazone, taken by mouth, was authorized for cerebral adrenoleukodystrophy.
USANew treatments and approvals
Through the accelerated pathway, the FDA has approved pariglasgene brecaparvovec for glycogen storage disease type Ia.
EuropeResearch and clinical trials
A total of 58 patients from 34 centers in seven European countries were followed.
These codes identify the disease in international classifications and databases. They can help when you talk with your doctor or look for reliable sources.
Orphanet code: ORPHA:394
No separate ICD-11 code; WHO classifies this disease under: 5C50.B
Codes checked against WHO ICD-11 and Orphanet on October 7, 2026.
This page provides general information and does not replace diagnosis or treatment. Talk to your doctor about symptoms, diagnosis and treatment.