| hereditary methemoglobinaemia | Methemoglobinaemia due to formation of any one of a group of abnormal a chain or b chain haemoglobins collectively known as haemoglobin M. Slate-gray cyanosis occurs in early infancy, without pulmonary or cardiac disease, and is resistant to ascorbic acid or methylene blue therapy; autosomal dominant inheritance, methemoglobinaemia due to deficiency of cytochrome b5 reductaseor methemoglobin reductase, the enzyme responsible for reduction of intraerythrocyte methemoglobin; cyanosis is improved by ascorbic acid or methylene blue; autosomal recessive inheritance, one case of methemoglobinaemia has been reported that apparently is due to a deficiency of cytochrome b5. Synonym: hereditary methemoglobinaemia, hereditary methemoglobinaemic cyanosis, primary methemoglobinaemia. (05 Mar 2000) |
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| hereditary methemoglobinaemic cyanosis | Methemoglobinaemia due to formation of any one of a group of abnormal a chain or b chain haemoglobins collectively known as haemoglobin M. Slate-gray cyanosis occurs in early infancy, without pulmonary or cardiac disease, and is resistant to ascorbic acid or methylene blue therapy; autosomal dominant inheritance, methemoglobinaemia due to deficiency of cytochrome b5 reductaseor methemoglobin reductase, the enzyme responsible for reduction of intraerythrocyte methemoglobin; cyanosis is improved by ascorbic acid or methylene blue; autosomal recessive inheritance, one case of methemoglobinaemia has been reported that apparently is due to a deficiency of cytochrome b5. Synonym: hereditary methemoglobinaemia, hereditary methemoglobinaemic cyanosis, primary methemoglobinaemia. (05 Mar 2000) |
| hereditary multiple exostoses | A disturbance of enchondral bone growth in which multiple, generally benign osteochondromas of long bones appear during childhood, commonly with shortening of the radius and fibula; the ill-effects are usually mechanical but malignant change is rare; autosomal dominant inheritance. Synonym: diaphysial aclasis, hereditary deforming chondrodystrophy, multiple exostosis, osteochondromatosis. (05 Mar 2000) |
| hereditary multiple trichoepithelioma | <tumour> Multiple small benign nodules, occurring mostly on the skin of the face, derived from basal cells of hair follicles enclosing small keratin cysts; frequent autosomal dominant inheritance. Synonym: acanthoma adenoides cysticum, Brooke's tumour, epithelioma adenoides cysticum, hereditary multiple trichoepithelioma. Origin: tricho-+ epithelioma (05 Mar 2000) |
| hereditary mutation | A gene change that occurs in a germ cell (an egg or sperm) to become incorporated in every cell in the body. Hereditary mutations (also called germline mutations) play a role in cancer as, for example, the eye tumour retinoblastoma and wilms' tumour of the kidney. (12 Dec 1998) |
| hereditary myokymia | A syndrome consisting of myokymia, hypoglycaemia, and disturbed thyroid function. (05 Mar 2000) |
| hereditary nephritis | <pathology> An inherited disorder involving damage to the kidneys, haematuria and hearing loss. In some individuals vision may also be affected. This genetic disease is uncommon. Symptoms include loss of hearing, abnormal colour to urine, swelling, cough and decline in vision. Inheritance: sex-linked autosomal dominant. Incidence: 1 in 50,000. (27 Sep 1997) |
| hereditary pancreatitis | <radiology> Rare, autosomal dominant, variable penetrance, onset often in childhood, on X-ray: large, round, peripherally dense calculi (12 Dec 1998) |
| hereditary peroneal nerve dysfunction | <neurology> A slowly progressive genetic disorder characterised by muscle atrophy in the feet and the legs, progressing to the hands and arms, due to a disorder involving the destruction of nerves (degeneration of the myelin sheath). Other features include foot drop and a slapping gait. There is no specific treatment for this disorder. (27 Sep 1997) |
| hereditary persistence of foetal haemoglobin | <haematology> Hereditary persistence of foetal haemoglobin is a genetic condition where adult types of haemoglobin fail to develop and the types of haemoglobin the individual had as a foetus remains present well past the point when they would normally have stopped being produced. (09 Oct 1997) |
| hereditary progressive arthro-ophthalmopathy | Autosomal dominant arthro-ophthalmopathy associated with progressive multiple dysplasia of the epiphyses, overtubulation of long bones, cleft lip and palate, hypermobility of joints, flattened vertebral bodies, pelvic bone deformities, and deafness. Synonym: Stickler's syndrome. (05 Mar 2000) |
| hereditary pyropoikilocytosis | A rare recessive disorder manifested by severe haemolysis, marked poikilocytosis, and a characteristic sensitivity of the red cells to heat-induced fragmentation in vitro; apparently due to a defect in spectrin self-association. Synonym: hereditary pyropoikilocytosis. (05 Mar 2000) |
| hereditary sensory radicular neuropathy | Neuropathy characterised by the occurrence of severe, relapsing foot ulcerations of neuropathic origin, destruction of terminal digits of feet and hands, and a loss of sensation; autosomal dominant inheritance is associated with onset in the second decade or later. (05 Mar 2000) |
| hereditary spherocytosis | <haematology> A hereditary disorder that leads to a chronic haemolytic anaemia due to an abnormality in the red blood cell membrane. This disorder is caused by a defective gene. Red cells are resistant to stress and rupture easily. Infants may appear jaundiced and pale. Fatigue, weakness and shortness of breath are other symptoms that may be seen in older patients. The spleen may also be enlarged. Treatment includes splenectomy (removal of the spleen). After this is accomplished the life-span of the red blood cells returns to normal. (27 Sep 1997) |
| hereditary spinal ataxia | Sclerosis of the posterior and lateral columns of the spinal cord, occurring in children and marked by ataxia in the lower extremities, extending to the upper, followed by paralysis and contractures; autosomal recessive inheritance. See: spinocerebellar ataxia. Synonym: Friedreich's ataxia, heredotaxia. (05 Mar 2000) |