Seizures-scoliosis-macrocephaly syndrome
Synonyms: SSM syndrome
- Type
- Disease
- Group
- Disorder
- Inheritance
- Autosomal recessive
- Age of onset
- Infancy
- Status
- active
Seizures-scoliosis-macrocephaly syndrome is a rare, genetic neurometabolic disorder characterized by seizures, macrocephaly, delayed motor milestones, moderate intellectual disability, scoliosis with no exostoses, muscular hypotonia present since birth, as well as renal dysfunction. Coarse facial features (including hypertelorism and long hypoplastic philtrum) and bilateral cryptorchidism (in males) are also commonly reported. Additional manifestations include abnormal gastrointestinal motility (resulting in constipation, diarrhea, gastroesophageal reflux and dysphagia), gait disturbances, strabismus and ventricular septal defects.
Names in Orphadata languages
12 of 12 languages| Lang | Name | Synonyms |
|---|---|---|
| en | Seizures-scoliosis-macrocephaly syndrome | SSM syndrome |
| fr | Syndrome de convulsions-scoliose-macrocéphalie | |
| de | Krämpfe-Skoliose-Makrozephalie-Syndrom | SSM-Syndrom |
| es | Síndrome de crisis-escoliosis-macrocefalia | |
| it | Sindrome crisi epilettiche - scoliosi - macrocefalia | |
| nl | Insulten - scoliose - macrocefalie-syndroom | SSM-syndroom |
| pt | Síndrome de convulsões-escoliose-macrocefalia | |
| pl | Zespół napadów padaczkowych, skoliozy i małogłowia | Zespół SSM |
| cs | Syndrom zahrnující křeče, skoliózu a makrocefalii | SSM syndrome · SSM syndrom |
| uk | Синдром судоми-сколіоз-макроцефалія | SSM-синдром |
| zh | 癫痫-脊髓灰质炎-大头畸形综合征 | SSM综合征 |
| tr | Nöbetler-skolyoz-makrosefali sendromu | SSM sendromu |
Definition in:
Cross-references
qualifier = Orphanet mapping relation| Source | Code | Qualifier | ICD relation | Validation |
|---|---|---|---|---|
| OMIM | 616682 | E | validated | |
| ICD-10 | Q87.8 | NTBT | attributed | validated |
| ICD-11 | 5C54.1 | NTBT | attributed | validated |
| MONDO | 0014731 | E | validated | |
| UMLS | C4225248 | E | validated |
E exact · NTBT this ORPHAcode is narrower than the target · BTNT broader than the target · ND not decided.
Classification
Preferential parent (Orphanet linearisation):
Parents in the classifications (3):
- ORPHA:371071Congenital disorder of glycosylation with epilepsy as a major feature
rare genetic diseases; rare neurological diseases - ORPHA:309450Disorder of O-xylosylglycan synthesis
rare inborn errors of metabolism; rare genetic diseases - ORPHA:611314Rare syndromic intellectual disability without multiple congenital anomalies/dysmorphic syndrome
rare genetic diseases; rare neurological diseases
No children.
Genes
1 direct| Gene | Association | Status | HGNC | Ensembl | OMIM | Locus | Name | Source of validation |
|---|---|---|---|---|---|---|---|---|
| EXT2 | Disease-causing germline mutation(s) (loss of function) in | Assessed | HGNC:3513 | ENSG00000151348 | 608210 | 11p11.2 | exostosin glycosyltransferase 2 | 26246518[PMID] |
Prevalence and incidence
2 records| Type | Class | Value | Area | Qualification | Validation | Source |
|---|---|---|---|---|---|---|
| Cases/families | 10 cases | Worldwide | Case(s) | Validated | 30997052[PMID] | |
| Point prevalence | <1 / 1 000 000 | — | Worldwide | Class only | Validated | ORPHANET_30997052[PMID] |
Value is Orphadata's ValMoy: the mean estimate per 100 000 for prevalence and incidence, the number of cases or families for case reports.
HPO phenotypes
31 annotations · validated 2020-01-03| HPO | Term (as annotated by Orphanet) | Diagnostic |
|---|---|---|
| Very frequent (99-80%) | ||
| HP:0000750 | Delayed speech and language development | |
| HP:0001263 | Global developmental delay | |
| HP:0004349 | Reduced bone mineral density | |
| HP:0001250 | Seizure | |
| Frequent (79-30%) | ||
| HP:0030680 | Abnormal cardiovascular system morphology | |
| HP:0000077 | Abnormality of the kidney | |
| HP:0000356 | Abnormality of the outer ear | |
| HP:0000951 | Abnormality of the skin | |
| HP:0000717 | Autism | |
| HP:0002136 | Broad-based gait | |
| HP:0000414 | Bulbous nose | |
| HP:0002019 | Constipation | |
| HP:0000028 | Cryptorchidism | |
| HP:0002020 | Gastroesophageal reflux | |
| HP:0000316 | Hypertelorism | |
| HP:0001252 | Hypotonia | |
| HP:0001256 | Intellectual disability, mild | |
| HP:0002342 | Intellectual disability, moderate | |
| HP:0000343 | Long philtrum | |
| HP:0000256 | Macrocephaly | |
| HP:0002018 | Nausea | |
| HP:0001845 | Overlapping toe | |
| HP:0002650 | Scoliosis | |
| Occasional (29-5%) | ||
| HP:0001631 | Atrial septal defect | |
| HP:0100777 | Exostoses | |
| HP:0004425 | Flat forehead | |
| HP:0000348 | High forehead | |
| HP:0010864 | Intellectual disability, severe | |
| HP:0000252 | Microcephaly | |
| HP:0001561 | Polyhydramnios | |
| HP:0011220 | Prominent forehead | |
Run the differential on the 4 obligate / very frequent terms
Annotation source: 30997052[PMID]_26246518[PMID]_30288735[PMID]
Sources for this card
- Orphanet page: orpha.net/en/disease/detail/466926
- This record as JSON: /data/d/466926.json