Clinical Trials Involving Rare Diseases: O
- Occipital Horn Syndrome (1)
- Ochronosis (8)
- Ocular Cicatricial Pemphigoid (4)
- Ocular Melanoma (52)
- Ocular Muscular Dystrophy (5)
- Ocular Toxoplasmosis (4)
- Oculocerebral Syndrome With Hypopigmentation (4,202)
- Oculocutaneous Albinism (14)
- Oculopharyngeal Muscular Dystrophy (12)
- Ogilvie Syndrome (2)
- Olfactory Neuroblastoma (64)
- Oligoastrocytoma (94)
- Oligodendroglioma (371)
- Olivopontocerebellar Atrophy (2)
- Ollier Disease (7)
- Omenn Syndrome (6)
- Onchocerciasis (24)
- Oncogenic Osteomalacia (12)
- Opsoclonus-myoclonus Syndrome (6)
- Optic Atrophy 1 (5)
- Optic Neuritis (129)
- Optic Pathway Glioma (42)
- Oral Cancer (459)
- Oral Leukoplakia (29)
- Oral Squamous Cell Carcinoma (48)
- Oral Submucous Fibrosis (9)
- Orbital Lymphoma (2)
- Organic Acidemias (11)
- Ornithine Transcarbamylase Deficiency (21)
- Orofaciodigital Syndromes (2)
- Oropharyngeal Cancer, Adult (10)
- Orotic Aciduria Type 1 (1)
- Osteochondritis Dissecans (26)
- Osteochondroma (20)
- Osteochondrosis (28)
- Osteofibrous Dysplasia (1)
- Osteogenesis Imperfecta (54)
- Osteogenesis Imperfecta Type II (1)
- Osteogenesis Imperfecta Type III (9)
- Osteogenesis Imperfecta Type IV (1)
- Osteogenesis Imperfecta Type VI (3)
- Osteomalacia (40)
- Osteomyelitis (85)
- Osteopetrosis (21)
- Osteopetrosis Autosomal Dominant Type 2 (1)
- Osteoporosis-pseudoglioma Syndrome (2)
- Osteosarcoma (535)
- Ostium Secundum Atrial Septal Defect (7)
- Oto-Palatal-digital Syndrome (2)
- Oto-palato-digital Syndrome Type 1 (2)
- Ovarian Cancer (2,699)
- Ovarian Carcinosarcoma (28)
- Ovarian Epithelial Cancer (2,525)
- Ovarian Germ Cell Tumor (183)
- Ovarian Low Malignant Potential Tumor (25)
- Ovarian Sex Cord Tumor With Annular Tubules (5)
- Ovarian Small Cell Carcinoma (3)