Clinical Trials Involving Rare Diseases: O
- Occipital Horn Syndrome (2)
- Ochronosis (9)
- Ocular Cicatricial Pemphigoid (4)
- Ocular Melanoma (62)
- Ocular Muscular Dystrophy (7)
- Ocular Toxoplasmosis (4)
- Oculo-auriculo-vertebral Spectrum (9)
- Oculocerebral Syndrome With Hypopigmentation (4,921)
- Oculocutaneous Albinism (14)
- Oculopharyngeal Muscular Dystrophy (12)
- Odontoma (1)
- Ogilvie Syndrome (3)
- Olfactory Neuroblastoma (66)
- Oligoastrocytoma (98)
- Oligodendroglioma (385)
- Olivopontocerebellar Atrophy (3)
- Ollier Disease (8)
- Omenn Syndrome (6)
- Onchocerciasis (28)
- Oncogenic Osteomalacia (14)
- Opisthorchiasis (1)
- Opsoclonus-myoclonus Syndrome (6)
- Optic Atrophy 1 (5)
- Optic Neuritis (160)
- Optic Pathway Glioma (43)
- Oral Cancer (536)
- Oral Leukoplakia (33)
- Oral Squamous Cell Carcinoma (184)
- Oral Submucous Fibrosis (9)
- Orbital Lymphoma (2)
- Organic Acidemias (16)
- Ornithine Transcarbamylase Deficiency (29)
- Orofaciodigital Syndromes (2)
- Oropharyngeal Cancer, Adult (10)
- Orotic Aciduria Type 1 (1)
- Osteochondritis Dissecans (27)
- Osteochondroma (27)
- Osteochondrosis (33)
- Osteofibrous Dysplasia (1)
- Osteogenesis Imperfecta (63)
- Osteogenesis Imperfecta Type II (1)
- Osteogenesis Imperfecta Type III (10)
- Osteogenesis Imperfecta Type IV (2)
- Osteogenesis Imperfecta Type VI (4)
- Osteomalacia (46)
- Osteomyelitis (100)
- Osteopetrosis (20)
- Osteopetrosis Autosomal Dominant Type 2 (1)
- Osteoporosis-pseudoglioma Syndrome (2)
- Osteosarcoma (615)
- Ostium Secundum Atrial Septal Defect (7)
- Oto-Palatal-digital Syndrome (2)
- Oto-palato-digital Syndrome Type 1 (2)
- Ovarian Cancer (3,085)
- Ovarian Carcinosarcoma (31)
- Ovarian Epithelial Cancer (2,881)
- Ovarian Germ Cell Tumor (186)
- Ovarian Low Malignant Potential Tumor (25)
- Ovarian Sex Cord Tumor With Annular Tubules (5)
- Ovarian Small Cell Carcinoma (4)