Obstructive sleep apnea is a condition in which individuals experience pauses in breathing (apnea) during sleep, which are associated with partial or complete closure of the throat (pper airway). Complete closure can lead to apnea while partial closu READ MORE

Ochoa syndrome is a disorder characterized by urinary problems and unusual facial expressions. The urinary problems associated with Ochoa syndrome typically become apparent in early childhood or adolescence. People with this disorder may have difficu READ MORE

Ocular albinism is a genetic condition that primarily affects the eyes. This condition reduces the coloring (pigmentation) of the iris, which is the colored part of the eye, and the retina, which is the light-sensitive tissue at the back of the eye. READ MORE

Oculocutaneous albinism is a group of conditions that affect the color of (pigmentation) of the skin, hair, and eyes. Affected individuals typically have very fair skin and white or light-colored hair. Long-term sun exposure greatly increases the ris READ MORE

Oculodentodigital dysplasia is a condition that affects many parts of the body, particularly the eyes (oculo-), teeth (dento-), and fingers (digital). The signs and symptoms of the condition vary widely among affected individuals. Some features of oc READ MORE

Oculofaciocardiodental (OFCD) syndrome is a condition that affects the development of the eyes (oculo-), facial features (facio-), heart (cardio-), and teeth (dental). The eye abnormalities associated with OFCD syndrome can affect one or both eyes. M READ MORE

Oculopharyngeal muscular dystrophy is a genetic condition characterized by muscle weakness that begins in adulthood, typically after age 40. The term "oculopharyngeal" refers to the eyes (oculo-) and a part of the throat called the pharynx (-pharynge READ MORE

The Maat-Kievit-Brunner type of Ohdo syndrome is a rare condition characterized by intellectual disability and distinctive facial features. It has only been reported in males. The intellectual disability associated with this condition varies from mil READ MORE

The Say-Barber-Biesecker-Young-Simpson (SBBYS) variant of Ohdo syndrome is a rare condition characterized by genital abnormalities in males, missing or underdeveloped kneecaps (patellae), intellectual disability, distinctive facial features, and abno READ MORE

Ollier disease is a disorder characterized by multiple enchondromas, which are noncancerous (benign) growths of cartilage that develop within the bones. These growths most commonly occur in the limb bones, especially in the bones of the hands and fee READ MORE

Omenn syndrome is an inherited disorder of the immune system (immunodeficiency). Omenn syndrome is one of several forms of severe combined immunodeficiency (SCID), a group of disorders that cause individuals to have virtually no immune protection fro READ MORE

Ophthalmo-acromelic syndrome is a condition that results in malformations of the eyes, hands, and feet. The features of this condition are present from birth. The eyes are often absent or severely underdeveloped (anophthalmia), or they may be abnorma READ MORE