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ORPHA:88618Disease
What it is
A rare, multisystemic inherited metabolic disease characterized clinically, by a variable spectrum of severity, primarily comprised of psychomotor delay, myopathy and liver dysfunction. Most patients present in infancy, but the onset can be already in utero or in adult age. Hypermethioninemia is frequent, but often absent in infancy. Creatine kinase is elevated in most patients.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Adolescent, Adult, Antenatal, Childhood, Infancy, Neonatal
- Inheritance
- Autosomal recessive
- Classified as
- Disease
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Very common80–99%
5Common30–79%
27- Abnormal facial shape
- Abnormality of coagulation
- Abnormality of the liver
- Atypical behavior
- Cerebellar hypoplasia
- CNS hypomyelination
- Delayed myelination
- Developmental regression
- Elevated circulating creatine kinase concentration
- Elevated coagulation factor V activity
- Esotropia
- Failure to thrive
- Floppy infant
- Global developmental delay
- Growth delay
- Hydrops fetalis
- Hyperintensity of cerebral white matter on MRI
- Hypofibrinogenemia
- Hypoplasia of the corpus callosum
- Hypoplasia of the pons
- Muscular dystrophy
- Poor head control
- Prolonged prothrombin time
- Reduced antithrombin III activity
- Reduced factor VII activity
- Short attention span
- Strabismus
Sometimes5–29%
12- Abnormality of hair texture
- Abnormality of the dentition
- Cardiomyopathy
- Hepatocellular carcinoma
- Hypermethioninemia
- Microcephaly
- Muscle weakness
- Pes planus
and 4 more in this range
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Gene
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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