mast syndrome
Findings
No curated finding names mast syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Autosomal recessive spastic paraplegia type 21 is a complex type of hereditary spastic paraplegia characterized by an onset in adolescence or adulthood of slowly progressive spastic paraparesis associated with the additional manifestations of apraxia, cognitive and speech decline (leading to dementia and akinetic mutism in some cases), personality disturbances and extrapyramidal (e.g. oromandibular dyskinesia, rigidity) and cerebellar (i.e. dysdiadochokinesia and incoordination) signs. Subtle abnormalities (e.g. developmental delays) may be noted earlier in childhood. A thin corpus callosum and white matter abnormalities are equally reported on magnetic resonance imaging.
Definition from the Mondo Disease Ontology (MONDO:0009568), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Slowly progressive · Childhood onset
HPO, annotations 2026-09-02
Features
31 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Babinski signHPOHP:0003487
- 14 of 14 reported patients
- Cerebellar atrophyHPOHP:0001272
- 3 of 3 reported patients
- Cerebral atrophyHPOHP:0002059
- 3 of 3 reported patients
- DementiaHPOHP:0000726
- 14 of 14 reported patients
- Very frequent (80% to 99% of cases)
- DysarthriaHPOHP:0001260
- 14 of 14 reported patients
- Gait disturbanceHPO
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- SPG21HGNC:20373
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2022
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
- Limited · Ambry Genetics · Autosomal recessive · 2019
Where it sits
- A kind of
Other names
2 names
Resolves to: mast syndrome
- Also called
- autosomal recessive spastic paraplegia type 21SPG21