Obsessive Compulsive disorder
Obstetric Brachial Plexus Palsy see Erb's Palsy
Occlusive Infantile Arteriopathy see Inherited Metabolic diseases
Occupational Lung diseases see Lung diseases
OCD see Obsessive Compulsive disorder
Ocular Albinism see Albinism
Ocular Muscular Dystrophy see Muscular Dystrophy and neuromuscular disorders
Ocular Myasthenia see Myasthenia Gravis and other Myasthenic syndromes
Oculo-Cerebro-Renal syndrome see Lowe syndrome
Oculo-Cutaneous Albinism see Albinism
Oculoauriculovertebral Dysplasia see Goldenhar syndrome
Oculopharyngeal Muscular Dystrophy see Muscular Dystrophy and neuromuscular disorders
Oesophageal Atresia see Tracheo-Oesophageal Fistula and/or Oesophageal Atresia
Ohdo Blepharophimosis syndrome see Ohdo syndrome
Ohdo syndrome
Ohtahara syndrome
Oligoarthritis see Arthritis (Juvenile Idiopathic)
Olivopontocerebellar Atrophy see Inherited Metabolic diseases
Ollier disease
Omenn's syndrome see Primary Immunodeficiencies
Omphalocele see Abdominal Exstrophies
Omphalocoele see Abdominal Exstrophies
Ondine's Curse see Congenital Central Hypoventilation syndrome
Ondine's see Congenital Central Hypoventilation syndrome
Opitz FG syndrome see Opitz-Kaveggia syndrome/FG syndrome
Opitz G/BBB syndrome
Opitz-Frias syndrome see Opitz G/BBB syndrome
Opitz-Kaveggia syndrome/FG syndrome