Gene/Protein Disease Symptom Drug Enzyme Compound
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 11,717 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Norepinephrine (NE), a vital neurotransmitter in both the central and peripheral nervous systems, is synthesized by dopamine beta-hydroxylase (DBH) through the oxidation of dopamine (DA) to NE. DBH deficiency is a congenital disorder characterized by severe orthostatic hypotension, ptosis, and retrograde ejaculation. Biochemical features of the syndrome include elevated levels of dopamine, undetectable levels of DBH, undetectable tissue and circulating levels of NE and epinephrine. Molecular genetic analysis studies suggested that DBH deficiency is a Mendelian recessive disorder attributable to heterogenous mutations at the DBH locus. DBH deficiency has been treated effectively with L-threo-3,4-dihydroxyphenylserine (DOPS). DOPS is converted directly to NE through decarboxylation by L-aromatic amino acid decarboxylase (AADC), thereby bypassing DBH. Orthostatic intolerance is a syndrome characterized by lightheadedness, fatigue, altered mentation, syncope, and postural tachycardia. Biochemical features may include plasma NE concentration that is disproportionately high in relation to sympathetic outflow, decreased NE clearance with standing, resistance to the NE-releasing effect of tyramine, and increased sensitivity to adrenergic agonists. A subset of OI patients has pathophysiologic features that have been associated with a genetic polymorphism. The coding mutation, A457P, occurs in one of the alleles of norepinephrine transporter gene of a proband with OI and her family. Alpha-methyl dopa, beta blockers and clonidine, a partial agonist of alpha2-adrenoceptor that acts centrally to reduce sympathetic outflow and lower blood pressure, have been effective in the treatment of this condition. The identification of the genetic polymorphisms involved in the synthesis, transport, storage, and metabolism of the catecholamines may provide new insights into the diagnosis and management of autonomic, cardiovascular, endocrine and psychiatric disorders.
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PMID:The broader view: catecholamine abnormalities. 1210 62

Norepinephrine and epinephrine are critical determinants of minute-to-minute regulation of blood pressure. Here we review the characterization of two syndromes associated with a genetic abnormality in the noradrenergic pathway. In 1986, we reported a congenital syndrome of undetectable tissue and circulating levels of norepinephrine and epinephrine, elevated levels of dopamine, and absence of dopamine-beta-hydroxylase (DBH). These patients appeared with ptosis and severe orthostatic hypotension and lacked sympathetic noradrenergic function. In two persons with DBH deficiency, we identified seven novel polymorphisms. Both patients are compound heterozygotes for a variant that affects expression of DBH protein via impairment of splicing. Patient 1 also has a missense mutation in DBH exon 2, and patient 2 carries missense mutations in exons 1 and 6. Orthostatic intolerance is a common syndrome affecting young women, presenting with orthostatic tachycardia and symptoms of cerebral hypoperfusion on standing. We tested the hypothesis that abnormal norepinephrine transporter (NET) function might contribute to its etiology. In our proband, we found an elevated plasma norepinephrine with standing that was disproportionate to the increase in levels of dihydroxphenylglycol, as well as impaired norepinephrine clearance and tyramine resistance. Studies of NET gene structure revealed a coding mutation converting a conserved alanine residue in transmembrane domain 9 to proline. Analysis of the protein produced by the mutant cDNA demonstrated greater than 98% reduction in activity relative to normal. The finding of genetic mutations responsible for DBH deficiency and orthostatic intolerance leads us to believe that genetic causes of other autonomic disorders will be found, enabling us to design more effective therapeutic interventions.
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PMID:Genetic basis of clinical catecholamine disorders. 1243 71