Clinical Trials Involving Rare Diseases: O
- Occipital Horn Syndrome (2)
- Ochronosis (9)
- Ocular Cicatricial Pemphigoid (4)
- Ocular Melanoma (64)
- Ocular Muscular Dystrophy (7)
- Ocular Toxoplasmosis (4)
- Oculo-auriculo-vertebral Spectrum (10)
- Oculocerebral Syndrome With Hypopigmentation (5,216)
- Oculocutaneous Albinism (14)
- Oculopharyngeal Muscular Dystrophy (12)
- Odontoma (1)
- Ogilvie Syndrome (3)
- Olfactory Neuroblastoma (66)
- Oligoastrocytoma (99)
- Oligodendroglioma (393)
- Olivopontocerebellar Atrophy (3)
- Ollier Disease (8)
- Omenn Syndrome (6)
- Onchocerciasis (30)
- Oncogenic Osteomalacia (14)
- Opisthorchiasis (1)
- Opsoclonus-myoclonus Syndrome (6)
- Optic Atrophy 1 (5)
- Optic Neuritis (170)
- Optic Pathway Glioma (44)
- Oral Cancer (565)
- Oral Leukoplakia (34)
- Oral Squamous Cell Carcinoma (200)
- Oral Submucous Fibrosis (10)
- Orbital Lymphoma (2)
- Organic Acidemias (18)
- Ornithine Transcarbamylase Deficiency (30)
- Orofaciodigital Syndromes (3)
- Oropharyngeal Cancer, Adult (10)
- Orotic Aciduria Type 1 (1)
- Osteochondritis Dissecans (27)
- Osteochondroma (28)
- Osteochondrosis (38)
- Osteofibrous Dysplasia (1)
- Osteogenesis Imperfecta (66)
- Osteogenesis Imperfecta Type I (1)
- Osteogenesis Imperfecta Type II (1)
- Osteogenesis Imperfecta Type III (11)
- Osteogenesis Imperfecta Type IV (2)
- Osteogenesis Imperfecta Type VI (6)
- Osteomalacia (48)
- Osteomyelitis (107)
- Osteopetrosis (20)
- Osteopetrosis Autosomal Dominant Type 2 (1)
- Osteoporosis-pseudoglioma Syndrome (2)
- Osteosarcoma (633)
- Ostium Secundum Atrial Septal Defect (7)
- Oto-Palatal-digital Syndrome (3)
- Oto-palato-digital Syndrome Type 1 (3)
- Ovarian Cancer (3,234)
- Ovarian Carcinosarcoma (32)
- Ovarian Epithelial Cancer (3,016)
- Ovarian Germ Cell Tumor (186)
- Ovarian Low Malignant Potential Tumor (25)
- Ovarian Sex Cord Tumor With Annular Tubules (6)
- Ovarian Small Cell Carcinoma (4)