Clinical Trials Involving Rare Diseases: O
- Occipital Horn Syndrome (1)
- Ochronosis (8)
- Ocular Cicatricial Pemphigoid (4)
- Ocular Melanoma (52)
- Ocular Muscular Dystrophy (3)
- Ocular Toxoplasmosis (4)
- Oculocerebral Syndrome With Hypopigmentation (4,039)
- Oculocutaneous Albinism (14)
- Oculopharyngeal Muscular Dystrophy (12)
- Ogilvie Syndrome (1)
- Olfactory Neuroblastoma (64)
- Oligoastrocytoma (93)
- Oligodendroglioma (367)
- Olivopontocerebellar Atrophy (2)
- Ollier Disease (7)
- Omenn Syndrome (6)
- Onchocerciasis (24)
- Oncogenic Osteomalacia (11)
- Opsoclonus-myoclonus Syndrome (6)
- Optic Atrophy 1 (5)
- Optic Neuritis (122)
- Optic Pathway Glioma (43)
- Oral Cancer (450)
- Oral Leukoplakia (28)
- Oral Squamous Cell Carcinoma (46)
- Oral Submucous Fibrosis (9)
- Orbital Lymphoma (2)
- Organic Acidemias (9)
- Ornithine Transcarbamylase Deficiency (19)
- Orofaciodigital Syndromes (2)
- Oropharyngeal Cancer, Adult (9)
- Orotic Aciduria Type 1 (1)
- Osteochondritis Dissecans (25)
- Osteochondroma (19)
- Osteochondrosis (26)
- Osteofibrous Dysplasia (1)
- Osteogenesis Imperfecta (52)
- Osteogenesis Imperfecta Type II (1)
- Osteogenesis Imperfecta Type III (8)
- Osteogenesis Imperfecta Type IV (1)
- Osteogenesis Imperfecta Type VI (3)
- Osteomalacia (39)
- Osteomyelitis (82)
- Osteopetrosis (21)
- Osteopetrosis Autosomal Dominant Type 2 (1)
- Osteoporosis-pseudoglioma Syndrome (2)
- Osteosarcoma (520)
- Ostium Secundum Atrial Septal Defect (6)
- Oto-Palatal-digital Syndrome (2)
- Oto-palato-digital Syndrome Type 1 (2)
- Ovarian Cancer (2,627)
- Ovarian Carcinosarcoma (27)
- Ovarian Epithelial Cancer (2,463)
- Ovarian Germ Cell Tumor (184)
- Ovarian Low Malignant Potential Tumor (25)
- Ovarian Sex Cord Tumor With Annular Tubules (5)
- Ovarian Small Cell Carcinoma (2)