Preferred Label : Sebastian syndrome;
Obsolete resource : true;
Moved to : 155100;
Symbol : SBS;
CISMeF acronym : SBS;
Type : Phenotype, molecular basis known;
Alternative titles and symbols : Sebastian platelet syndrome; Macrothrombocytopenia with dispersed leukocytic inclusions;
Description : Sebastian syndrome is an autosomal dominant disorder characterized by the triad of
thrombocytopenia, giant platelets, and inclusions in peripheral blood leukocytes (Greinacher
et al., 1990). There are several other disorders caused by mutation in the MYH9 gene
that share overlapping features with Sebastian syndrome. May-Hegglin anomaly (155100)
shares the same triad as Sebastian syndrome, but has a different ultrastructural appearance
of the leukocyte inclusions. In May-Hegglin anomaly, the inclusions are composed of
clusters of ribosomes oriented along parallel microfilaments, whereas in Sebastian
syndrome, the leukocyte inclusions are composed of highly dispersed filaments and
few ribosomes. Fechtner syndrome (153640) has the platelet defect accompanied by nephritis,
hearing loss, and eye abnormalities, mostly cataracts. Epstein syndrome (153650) has
the platelet defect, deafness, and nephritis, but does not have cataract and lacks
leukocyte inclusion bodies on classic staining of peripheral blood smears. The findings
of nephritis, hearing loss, and occasional cataracts in Fechtner and Epstein syndromes
are reminiscent of Alport syndrome (301050). Seri et al. (2003) suggested that these
4 disorders, May-Hegglin, Sebastian, Epstein, and Fechtner syndromes, are not distinct
entities, but rather represent a single disorder with a continuous clinical spectrum,
for which they proposed the term 'MYH9-related disease.' However, other disorders,
e.g., macrothrombocytopenia and progressive sensorineural deafness (600208) and a
form of nonsyndromic deafness (DFNA17; 603622), are also caused by mutation in the
MYH9 gene.;
Inheritance : Autosomal dominant;
Molecular basis : Caused by mutation in myosin, heavy chain 9, non-muscle gene (myh9,160775.0001);
Laboratory abnormalities : Mild to moderate thrombocytopenia (40-120 x 10(9)/l); Median mean platelet volume (mpv) 18fl; Mildly prolonged bleeding time 10-12 minutes; Normal platelet aggregation response to arachidonic acid (aa), adenosine5'-diphosphate
(adp), collagen, and ristocetin;
Prefixed ID : 605249;
Origin ID : 605249;
UMLS CUI : C1854520;
Currated CISMeF NLP mapping
- False automatic mappings
- HPO term(s)
- Not associated HPO term(s)
- ORDO concept(s)
- See also inter- (CISMeF)
- Semantic type(s)
- UMLS correspondences (same concept)
