Diseases

Orbital lymphoma

A tumor that develops in the soft tissue of the eye socket and can push against the eye causing problems with vision and eye movement.

Organic acidemia

Organic acidemia, also called organic aciduria, is a term used to classify a group of metabolic disorders which disrupt normal amino acid metabolism, particularly branched-chain amino acids, causing a buildup of acids which are usually not present.

Organic brain syndrome

Organic brain syndrome is a general term referring to many acute and chronic physical disorders that cause impaired mental function. It does not usually include psychiatric disorders. Though OBS is a common diagnosis in the elderly, it is related to disease processes and is not an inevitable part of aging.

Organic mood syndrome

Persistant mood changes due to physical causes such as a chemical imbalance rather than psychiatric causes. The duration and severity of the condition is determined by the nature and location of the cause.

Organic personality syndrome

Persistant personality changes due to physical causes such as a chemical imbalance rather than psychiatric causes. The duration and severity of the condition is determined by the nature and location of the cause.

Ornithine Transcarbamylase Deficiency

Ornithine Transcarbamylase Deficiency ( OTCD) is an inherited disorder that causes ammonia to accumulate in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The nervous system is especially sensitive to the effects of excess ammonia. Ornithine transcarbamylase deficiency often becomes evident in the first few days of life. An infant with ornithine transcarbamylase deficiency may be lacking in energy (lethargic) or unwilling to eat, and have poorly-controlled breathing rate or body temperature. Some babies with this disorder may experience seizures or unusual body movements, or go into a coma. Complications from ornithine transcarbamylase deficiency may include developmental delay and intellectual disability. Progressive liver damage, skin lesions, and brittle hair may also be seen.

Ornithinemia

A toxic condition occasionally producing localized cerebral swelling, caused by abnormal amounts of ornithine in the blood. [ornithine + G. haima, blood] Source: Stedman's Medical Spellchecker, © 2006 Lippincott Williams & Wilkins. All rights reserved.

Oro acral syndrome

A very rare syndrome characterized mainly by mouth and limb abnormalities.

Orofaciodigital syndrome 4

A rare inherited disorder characterized by facial, digital and oral abnormalities. Type IV is differentiated from the other types by the presence of severe shinbone deformity.

Orofaciodigital syndrome type1

A rare genetic disorder characterized by variable malformations of the face, digits and inside the mouth. Type 1 is distinguished from the other types of this condition by the presence of polycystic kidneys and a X-linked dominant inheritance

Oropharyngeal cancer- adult

Cancer of the back of the mouth which forms part of the throat including the back of the tongue, tonsils, part of the throat wall and soft palate (oropharynx).

Orotic aciduria hereditary

A rare metabolic disorder where an inherited enzyme deficiency (lack of orotidylic pyrophosphorylase and orotidylic decarboxylase or a lack of orotidylic decarboxylase only) impairs the body's ability to break down orotic acid, leading to excessive excretion of orotic acid in urine. It causes a characteristic form of anemia and may be associated with mental and physical retardation.

Orotic aciduria purines-pyrimidines

This is a rare, X-linked, recessive disorder caused by deficiency of hypoxanthine-guanine phosphoribosyl transferase (HPRT); degree of deficiency (and hence manifestations) vary with the specific mutation. HPRT deficiency results in failure of the salvage pathway for hypoxanthine and guanine. These purines are instead degraded to uric acid. Additionally, a decrease in inositol monophosphate and guanosyl monophosphate leads to an increase in conversion of 5-phosphoribosyl-1-pyrophosphate (PRPP) to 5-phosphoribosylamine, which further exacerbates uric acid overproduction. Hyperuricemia predisposes to gout and its complications. Patients also have a number of cognitive and behavioral dysfunctions, etiology of which is unclear; they do not appear related to uric acid.

Oroticaciduria 1

A rare metabolic disorder where deficiency of two enzymes (orotidylic pyrophosphorylase and orotidylic decarboxylase) which impairs the body's ability to break down orotic acid which then builds up in the body where it can cause damage.

Orotidylic decarboxylase deficiency

A rare metabolic disorder where deficiency of an enzyme (orotidylic decarboxylase) which impairs the body's ability to break down orotic acid which then builds up in the body where it can cause damage.

Orthostatic Hypotension

Orthostatic hypotension, colloquially known as head rush or dizzy spell, is a form of low blood pressure in which a person's blood pressure falls when suddenly standing up or stretching. In medical terms, it is defined as a fall in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg when a person assumes a standing position.

Orthostatic intolerance

A condition where various symptoms occur when a person moves to an upright position such as standing after sitting down or sitting up after lying down. It is due to problems with blood flow, blood pressure and heart rate

Oslam syndrome

A very rare syndrome characterized mainly by bone cancer, limb abnormalities and enlarged red blood cells.

Osler Rendu Weber syndrome 3

A rare genetic disorder characterized by nosebleeds and multiple telangiectases that can occur on the skin, mucosal lining and internal organs. The occurrence of pulmonary arteriovenus fistulas in type 3 is greater than type 2 but less than in type 1. It has a different genetic origin to type 1 and 3 (defect on chromosome 5q31.3-q32).

Osler-Rendu-Weber syndrome 2

A rare genetic disorder characterized by nosebleeds and multiple telangiectases that can occur on the skin, mucosal lining and internal organs. Type 2 tends to have a later onset than type 1 and there is a greater degree of liver involvement. It has a different genetic origin to type 1 and 3 (defect on chromosome 12q11-q14).

OSMED Syndrome

Otospondylomegaepiphyseal dysplasia (OSMED) is an autosomal recessive disorder of bone growth that results in skeletal abnormalities, severe hearing loss, and distinctive facial features. The name of the condition indicates that it affects hearing (oto-) and the bones of the spine (spondylo-), and enlarges the ends of bones (megaepiphyses)

Ossification of the posterior longitudinal ligament of the spine

Abnormal calcification of a spinal ligament. The progressive calcification can starts within months of birth and affects the ability to move arms and legs. The severity of the condition is highly variable with most patients noticing symptoms in the sixth decade