MASA syndrome
Findings
No curated finding names MASA syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
MASA syndrome (Mental retardation, Aphasia, Spastic paraplegia, Adducted thumbs) is a historical term used to describe a phenotype now considered to be part of the X-linked L1 clinical spectrum (L1 syndrome). MASA is characterized by mild to moderate intellectual deficit, delayed development of speech, hypotonia progressing to spasticity or spastic paraplegia, adducted thumbs, and mild to moderate distension of the cerebral ventricles.
Definition from the Mondo Disease Ontology (MONDO:0010559), read 2026-09-29. CC BY 4.0.
Features
13 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.
- AphasiaHPOHP:0002381
- Very frequent (80% to 99% of cases)
- Delayed speech and language developmentHPOHP:0000750
- Very frequent (80% to 99% of cases)
- Gait disturbanceHPOHP:0001288
- Very frequent (80% to 99% of cases)
- Hand clenchingHPOHP:0001188
- Very frequent (80% to 99% of cases)
- Hemiplegia/hemiparesisHPOHP:0004374
- Very frequent (80% to 99% of cases)
- HyperreflexiaHPOHP:0001347
- Very frequent (80% to 99% of cases)
Show the remaining 1
- VentriculomegalyHPOHP:0002119
- Occasional (5% to 29% of cases)
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.
- L1CAMHGNC:6470
- Strong · Genomics England PanelApp · X-linked · 2021
- Supportive · Orphanet · X-linked · 2021
Where it sits
Other names
4 names
Resolves to: MASA syndrome
- Also called
- Gareis-Mason syndromeintellectual disability-aphasia-shuffling gait-adducted thumbs syndromemasa syndrome, X-linked recessivespastic paraplegia, X-linked