DEFINITION
The disease definition according to a specific consensus conference or to The Diseases Database based on the Unified Medical Language System (NLM)
Also the link to the corresponding Mesh term has to be created
Se ci sono più voci su OMIM usare questo formato di ricerca:
Autism
EPIDEMIOLOGY
age, sex, seasonality, etc
SYMPTOMS
DIAGNOSIS
histopathology
radiology
NMR
laboratory tests
PATHOGENESIS
PATIENT RISK FACTORS
Vascular
Genetic
Acquired
Hormonal
Genetic
Acquired
TISSUE SPECIFIC RISK FACTORS
anatomical (due its structure)
vascular (due to the local circulation)
physiopathological (due to tissue function and activity)
COMPLICATIONS
THERAPY
homocystinuria betaine
Human homocysteine catabolism: three major pathways and their relevance to development of arterial occlusive disease. 1996
- Two separate metabolic pathways that methylate homocysteine to methionine are known in humans, utilizing, respectively, 5-methyltetrahydrofolate and betaine as methyl donors. Deficiency of the folate-dependent methylation system is linked to hyperhomocysteinemia. Our data suggest that this deficiency leads to concurrent metabolic down-regulation of homocysteine transsulfuration that may contribute to hyperhomocysteinemia. By contrast, no instances have been reported of hyperhomocysteinemia resulting from deficiencies of betaine-dependent homocysteine methylation. Long-term betaine supplementation of 10 patients, who had pyridoxine-resistant homocystinuria and gross hyperhomocysteinemia due to deficiency of cystathionine beta-synthase activity, caused a substantial lowering of plasma homocysteine, which has now been maintained for periods of up to 13 years. Betaine had to be taken regularly because the effect soon disappeared when treatment was stopped. In conclusion, depressed activity of the transsulfuration pathway may contribute to hyperhomocysteinemia because of primary deficiencies of enzymes of either the transsulfuration or of the folate-dependent methylation pathways. Stimulation of betaine-dependent homocysteine remethylation causes a commensurate decrease in plasma homocysteine that can be maintained as long as betaine is taken.
