The DBH gene provides instructions for producing the enzyme dopamine beta (β)-hydroxylase. This enzyme converts dopamine to norepinephrine, both of which are chemical messengers (neurotransmitters) that transmit signals between nerve cells. Norepinephrine plays an important role in the autonomic nervous system, which controls involuntary body processes such as the regulation of blood pressure and body temperature.
At least six mutations in the DBH gene have been found to cause dopamine β-hydroxylase deficiency. The most common mutation (usually written as IVS1+2T>C) interferes with the normal processing of dopamine β-hydroxylase. As a result of this mutation, an abnormally short, nonfunctional version of the enzyme is produced. A lack of functional dopamine β-hydroxylase leads to a shortage of norepinephrine, which causes difficulty with regulating blood pressure and other autonomic nervous system problems seen in dopamine β-hydroxylase deficiency.
Studies have shown certain variations (polymorphisms) in the DBH gene to be associated with increased risk of attention deficit hyperactivity disorder (ADHD). DBH gene polymorphisms are also thought to increase the risk of psychotic symptoms in people with schizophrenia or unipolar major depression. Other studies, however, have not supported these findings. Many genetic and environmental factors are believed to contribute to these complex conditions.
- dopamine beta-hydroxylase (dopamine beta-monooxygenase)
- dopamine beta-monooxygenase
- Basic Neurochemistry (sixth edition, 1999): Biosynthesis of Catecholamines
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- Endocrinology (first edition, 2001): Catecholamine synthesis and secretion
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