Clinical Trials Involving Rare Diseases: O
- Occipital Horn Syndrome (2)
- Ochronosis (9)
- Ocular Cicatricial Pemphigoid (4)
- Ocular Melanoma (54)
- Ocular Muscular Dystrophy (6)
- Ocular Toxoplasmosis (4)
- Oculocerebral Syndrome With Hypopigmentation (4,503)
- Oculocutaneous Albinism (14)
- Oculopharyngeal Muscular Dystrophy (12)
- Ogilvie Syndrome (3)
- Olfactory Neuroblastoma (66)
- Oligoastrocytoma (97)
- Oligodendroglioma (376)
- Olivopontocerebellar Atrophy (2)
- Ollier Disease (8)
- Omenn Syndrome (6)
- Onchocerciasis (26)
- Oncogenic Osteomalacia (13)
- Opsoclonus-myoclonus Syndrome (6)
- Optic Atrophy 1 (5)
- Optic Neuritis (138)
- Optic Pathway Glioma (42)
- Oral Cancer (498)
- Oral Leukoplakia (31)
- Oral Squamous Cell Carcinoma (173)
- Oral Submucous Fibrosis (9)
- Orbital Lymphoma (2)
- Organic Acidemias (14)
- Ornithine Transcarbamylase Deficiency (24)
- Orofaciodigital Syndromes (2)
- Oropharyngeal Cancer, Adult (10)
- Orotic Aciduria Type 1 (1)
- Osteochondritis Dissecans (26)
- Osteochondroma (22)
- Osteochondrosis (30)
- Osteofibrous Dysplasia (1)
- Osteogenesis Imperfecta (56)
- Osteogenesis Imperfecta Type II (1)
- Osteogenesis Imperfecta Type III (10)
- Osteogenesis Imperfecta Type IV (2)
- Osteogenesis Imperfecta Type VI (4)
- Osteomalacia (44)
- Osteomyelitis (91)
- Osteopetrosis (21)
- Osteopetrosis Autosomal Dominant Type 2 (1)
- Osteoporosis-pseudoglioma Syndrome (2)
- Osteosarcoma (581)
- Ostium Secundum Atrial Septal Defect (7)
- Oto-Palatal-digital Syndrome (2)
- Oto-palato-digital Syndrome Type 1 (2)
- Ovarian Cancer (2,848)
- Ovarian Carcinosarcoma (29)
- Ovarian Epithelial Cancer (2,666)
- Ovarian Germ Cell Tumor (185)
- Ovarian Low Malignant Potential Tumor (25)
- Ovarian Sex Cord Tumor With Annular Tubules (5)
- Ovarian Small Cell Carcinoma (3)