Rare diseases · Sign or symptom
Hyperhomocystinemia
Elevated blood homocystine
HP:0002160
What it means
An increased concentration of homocystine in the blood.
Homocystine is a disulfide derivative of homocysteine (a precursor of cysteine). Hyperhomocystinemic patients show blood homocystine levels in the range of 50-200 micromolar.
Rare diseases that can present with this9
Very common80–99%
6- Homocystinuria due to cystathionine beta-synthase deficiency
- Homocystinuria due to methylene tetrahydrofolate reductase deficiency
- Methylcobalamin deficiency type cblE
- Methylmalonic acidemia with homocystinuria, type cblC
- Methylmalonic acidemia with homocystinuria type cblF
- S-adenosylhomocysteine hydrolase deficiency
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Homocystinemia
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.