O
Obesity
Obstructive apnea (use: Sleep apnea syndromes)
Oculocerebrorenal syndrome (use: Lowe syndrome)
Oral cancer
Organic acidemia
Organic mental disorders
Orphan diseases (use: Rare diseases)
Orthopedic diseases (use: Bone diseases)
Orthopedic disorders (use: Bone diseases)
Osgood Schlatter disease (use: Osteochondritis)
Osteoarthritis
Osteoarthrosis (use: Osteoarthritis)
Osteochondritis
Osteochondrosis (use: Osteochondritis)
Osteogenesis imperfecta
Osteoporosis
Otitis media
Ovarian cancer
Ovarian diseases
Overweight (use: Obesity)