Medical Syndromes: Definition, Diagnosis, and Examples
A syndrome is a recognizable constellation of signs (objective findings) and symptoms (subjective experiences) that consistently occur together, indicating a specific pathophysiological process or disease entity.
Key Features
- Non-specificity: Individual features may occur in other conditions; the pattern is diagnostic.
- Eponymous naming: Often after discoverer (Down, Marfan, Turner, Klinefelter, Noonan, Williams, Prader-Willi).
- Etiology: Genetic (chromosomal, single-gene), teratogenic, infectious, autoimmune, neoplastic, multifactorial.
- Variable expressivity/penetrance: Same syndrome manifests differently across individuals.
Diagnosis
- Clinical criteria (major/minor features)
- Genetic testing (karyotype, microarray, sequencing)
- Biomarkers, imaging, functional studies
Examples
| Syndrome | Type | Key Features |
|---|---|---|
| Down (Trisomy 21) | Chromosomal | ID, characteristic facies, CHD, hypotonia, ↑ leukemia risk |
| Marfan (FBN1) | Connective tissue | Tall, arachnodactyly, lens dislocation, aortic root dilation |
| Turner (45,X) | Chromosomal | Female, short stature, ovarian dysgenesis, coarctation |
| Klinefelter (47,XXY) | Chromosomal | Male, tall, small testes, infertility, gynecomastia |
| Noonan (RASopathy) | Genetic | Short stature, webbed neck, CHD (pulmonic stenosis), bleeding |
| Cushing | Endocrine | Hypercortisolism: central obesity, striae, HTN, glucose intolerance |
| Metabolic | Multifactorial | Central obesity, HTN, dysglycemia, dyslipidemia |