Clinical Trials Involving Rare Diseases: O
- Occipital Horn Syndrome (1)
- Ochronosis (7)
- Ocular Cicatricial Pemphigoid (4)
- Ocular Melanoma (51)
- Ocular Muscular Dystrophy (3)
- Ocular Toxoplasmosis (4)
- Oculocutaneous Albinism (14)
- Oculopharyngeal Muscular Dystrophy (12)
- Ogilvie Syndrome (1)
- Olfactory Neuroblastoma (64)
- Oligoastrocytoma (92)
- Oligodendroglioma (365)
- Olivopontocerebellar Atrophy (2)
- Ollier Disease (7)
- Omenn Syndrome (5)
- Onchocerciasis (24)
- Oncogenic Osteomalacia (11)
- Opsoclonus-myoclonus Syndrome (6)
- Optic Atrophy 1 (5)
- Optic Neuritis (119)
- Optic Pathway Glioma (43)
- Oral Cancer (432)
- Oral Leukoplakia (27)
- Oral Squamous Cell Carcinoma (40)
- Oral Submucous Fibrosis (7)
- Orbital Lymphoma (2)
- Organic Acidemias (10)
- Ornithine Transcarbamylase Deficiency (17)
- Orofaciodigital Syndromes (2)
- Oropharyngeal Cancer, Adult (9)
- Orotic Aciduria Type 1 (1)
- Osteochondritis Dissecans (24)
- Osteochondroma (18)
- Osteochondrosis (26)
- Osteofibrous Dysplasia (1)
- Osteogenesis Imperfecta (51)
- Osteogenesis Imperfecta Type II (1)
- Osteogenesis Imperfecta Type III (8)
- Osteogenesis Imperfecta Type IV (1)
- Osteogenesis Imperfecta Type VI (3)
- Osteomalacia (40)
- Osteomyelitis (79)
- Osteopetrosis (19)
- Osteopetrosis Autosomal Dominant Type 2 (1)
- Osteoporosis-pseudoglioma Syndrome (2)
- Osteosarcoma (500)
- Ostium Secundum Atrial Septal Defect (5)
- Oto-Palatal-digital Syndrome (2)
- Oto-palato-digital Syndrome Type 1 (2)
- Ovarian Cancer (2,511)
- Ovarian Carcinosarcoma (27)
- Ovarian Epithelial Cancer (2,357)
- Ovarian Germ Cell Tumor (184)
- Ovarian Low Malignant Potential Tumor (25)
- Ovarian Sex Cord Tumor With Annular Tubules (5)
- Ovarian Small Cell Carcinoma (2)