Learning Objective: At the end of this lesson, the learner will be able to identify common autosomal dominant disorders, understand their inheritance patterns, and recognize key clinical features relevant to USMLE Step 1.
High-Yield Autosomal Dominant Diseases
| Disorder | Key Features / Notes |
|---|---|
| Achondroplasia | Short-limbed dwarfism; FGFR3 mutation |
| Autosomal Dominant Polycystic Kidney Disease (ADPKD) | Bilateral renal cysts; hypertension; intracranial aneurysms |
| Familial Adenomatous Polyposis (FAP) | Hundreds of colonic polyps; APC mutation; high colorectal cancer risk |
| Familial Hypercholesterolemia | LDL receptor defect; premature atherosclerosis; tendon xanthomas |
| Hereditary Hemorrhagic Telangiectasia | Osler-Weber-Rendu; telangiectasias; epistaxis; AVMs |
| Hereditary Spherocytosis | RBC membrane defect; hemolytic anemia; splenomegaly |
| Huntington Disease | CAG trinucleotide repeat; neurodegeneration; chorea; psychiatric symptoms |
| Li-Fraumeni Syndrome | TP53 mutation; multiple cancers, including sarcomas, breast cancer |
| Marfan Syndrome | FBN1 mutation; tall stature, aortic aneurysm, lens dislocation |
| Multiple Endocrine Neoplasias (MEN 1/2) | Tumors in endocrine glands (parathyroid, pancreas, pituitary; pheochromocytoma, medullary thyroid) |
| Myotonic Muscular Dystrophy | CTG trinucleotide repeat; myotonia, muscle wasting, cataracts |
| Neurofibromatosis Type 1 | Café-au-lait spots, neurofibromas, Lisch nodules |
| Neurofibromatosis Type 2 | Bilateral vestibular schwannomas, meningiomas |
| Tuberous Sclerosis | Hamartomas in multiple organs; seizures; mental retardation |
| Von Hippel-Lindau Disease | Hemangioblastomas, pheochromocytoma, renal cell carcinoma |
High-Yield Tips
- Autosomal dominant disorders often show vertical transmission (multiple generations).
- Pleiotropy is common: one gene affects multiple organ systems.
- Penetrance may be incomplete, and expressivity variable.
