Diseases

Oligomeganephrony

A very rare syndrome characterized by abnormal development of the kidneys which results in early kidney failure.

Oligophernia

Subnormal intellectual functioning which originates during the developmental period. This has multiple potential etiologies, including genetic defects and perinatal insults. Intelligence quotient (IQ) scores are commonly used to determine whether an individual is mentally retarded. IQ scores between 70 and 79 are in the borderline mentally retarded range. Scores below 67 are in the retarded range. (Joynt, Clinical Neurology, 1992, Ch55, p28)

Oliver McFarlane syndrome

A rare genetic condition characterized by mental retardation, dwarfism, retinal pigmentary degeneration and hairy eyelashes and eyebrows

Oliver syndrome

A very rare inherited disorder characterized by scalp, skull and limb abnormalities. The range and severity of the symptoms can vary greatly from mild to severe.

Olivopontocerebellar atrophies

Olivopontocerebellar atrophy (OPCA) is a term that describes the degeneration of neurons in specific areas of the brain – the cerebellum, pons, and inferior olives. OPCA is present in several neurodegenerative syndromes, including inherited and non-inherited forms of ataxia (such as the hereditary spinocerebellar ataxia known as Machado-Joseph disease) and multiple system atrophy (MSA), with which it is primarily associated.

Olivopontocerebellar atrophy type 3

A disorder where degeneration of certain parts of the brain and spinal cord results in symptoms such as blindness, tremor, speech problems and ataxia.

Ollier disease

A rare genetic disorder characterized by abnormal bone development.

Olmsted syndrome

A rare congenital condition characterized by progressive thickening and hardening of skin on palms and soles, alopecia and nail abnormalities

Omenn syndrome

Omenn syndrome is an autosomal recessive severe combined immunodeficiency associated with mutations in the recombination activating genes (RAG1 and RAG2), affecting circulating levels of both B-cells and T-cells.

Omodysplasia type 1

very rare syndrome characterized mainly by extremely short stature due to short bones in the arms and legs.

Omphalocele exstrophy imperforate anus

A very rare syndrome characterized mainly by the absence of an anal opening, spine defects and omphalocele (abdominal organ protruding from the belly button).

Omphalomesenteric cyst

A very rare umbilical disorder where the omphalomesenteric duct that forms in the early fetal stages fails to disappear during the first couple of months of development and results in the formation of a cyst. The cyst can become infected

Omsk hemorrhagic fever

A hemorrhagic fever caused by a virus. A serious outbreak occurred in Omsk and hence the name. Transmission occurs through tick bites. The infection has two phases: the first acute phase involves symptoms such as fever, rash and muscle pain and the second phase occurs after a week or two and involves the central nervous system (e.g. delirium, convulsions).

Onchocerciasis

Onchocerciasis, is a disease caused by infection with the parasitic worm Onchocerca volvulus. Symptoms include severe itching, bumps under the skin, and blindness. It is the second most common cause of blindness due to infection, after trachoma.

Oncogenic osteomalacia

Oncogenic osteomalacia (also known as tumor-induced osteomalacia or oncogenic hypophosphatemic osteomalacia), is an uncommon disorder resulting in increased renal phosphate excretion, hypophosphatemia and osteomalacia.

Ophthalmoplegic Muscular dystrophy

A rare disorder characterized by progressive weakness and wasting of the muscles around the eyes. Swallowing muscles may eventually become involved as well.

Opisthorchiasis

Infection with a type of fluke (Southeast Asian liver fluke or cat liver fluke). Infection usually occurs by consuming infected undercooked fish. Acute infection may cause fever, joint pain, rash, eosinophilia and lymphadenopathy where as chronic infections may cause enlarged liver, malnutrition. Mild cases can cause constipation, diarrhea and abdominal pain. Occasionally, the infection may be asymptomatic and in the other extreme, severe cases may result in complications such as cholangiocarcinoma.

Opitz syndrome

Smith-Lemli-Opitz syndrome is a developmental disorder that affects many parts of the body. This condition is characterized by distinctive facial features, small head size (microcephaly), intellectual disability or learning problems, and behavioral problems. Many affected children have the characteristic features of autism, a developmental condition that affects communication and social interaction. Malformations of the heart, lungs, kidneys, gastrointestinal tract, and genitalia are also common. Infants with Smith-Lemli-Opitz syndrome have weak muscle tone (hypotonia), experience feeding difficulties, and tend to grow more slowly than other infants. Most affected individuals have fused second and third toes (syndactyly), and some have extra fingers or toes (polydactyly).

Oppositional defiant disorder

Oppositional defiant disorder is a psychiatric category listed in the Diagnostic and Statistical Manual of Mental Disorders where it is described as an ongoing pattern of disobedient, hostile, and defiant behavior toward authority figures which goes beyond the bounds of normal childhood behavior.

Opsismodysplasia

A rare disorder where abnormal bone development results in skeletal abnormalities such as short stature, short limbs and facial abnormalities.

Opsoclonus Myoclonus Syndrome

Dancing eyes-dancing feet syndrome, is a rare neurological disorder of unknown causes which appears to be the result of an autoimmune process involving the nervous system. It is an extremely rare condition, affecting as few as 1 in 10,000,000 people per year. It affects 2 to 3% of children with neuroblastoma and has been reported to occur with celiac disease.