Dopamine beta-hydroxylase deficiency

Dopamine beta-hydroxylase deficiency is a condition that affects the autonomic nervous system, which controls involuntary body processes such as the regulation of blood pressure and body temperature. The signs and symptoms of dopamine beta-hydroxylase deficiency are caused by a lack of norepinephrine, one of the main chemical messengers (neurotransmitters) of the autonomic nervous system.

Although the signs and symptoms of dopamine beta-hydroxylase deficiency can appear during infancy, people often do not receive a diagnosis until their symptoms worsen during adolescence. Early signs and symptoms may include droopy eyelids (ptosis) and low blood pressure (hypotension). Infants with dopamine beta-hydroxylase deficiency may also experience vomiting, dehydration, decreased body temperature, and low blood glucose (hypoglycemia), which may lead to frequent hospitalizations.

By adolescence or early adulthood, people with dopamine beta-hydroxylase deficiency often have a sharp drop in blood pressure upon standing (orthostatic hypotension), which can cause dizziness, blurred vision, or fainting. Affected individuals typically experience extreme fatigue during exercise (exercise intolerance) due to their problems maintaining a normal blood pressure.

Other features of dopamine beta-hydroxylase deficiency include nasal congestion, an inability to stand for a prolonged period of time, and retrograde ejaculation, which is a discharge of semen backwards into the bladder.

Symptoms of dopamine beta-hydroxylase deficiency may improve with treatment. If the condition is not treated, symptoms often worsen during adolescence.

Dopamine beta-hydroxylase deficiency is a very rare disorder. As of 2021, approximately 25 individuals with this condition have been described in the scientific literature. 

Variants (also called mutations) in the DBH gene cause dopamine beta-hydroxylase deficiency. The DBH gene provides instructions for producing the enzyme dopamine beta-hydroxylase. This enzyme converts dopamine to norepinephrine. Both dopamine and norepinephrine are neurotransmitters that transmit signals from nerve cells to other cells in the body.

The variants in the DBH gene that cause dopamine beta-hydroxylase deficiency prevent the dopamine beta-hydroxylase enzyme from functioning properly. People who lack functional dopamine beta-hydroxylase cannot convert dopamine to norepinephrine. This leads to orthostatic hypotension, exercise intolerance, and the other autonomic nervous system problems seen in people with dopamine beta-hydroxylase deficiency.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell must have a variant to cause the disorder. The parents of an individual with an autosomal recessive condition each carry one copy of the altered gene, but they typically do not show signs and symptoms of the condition.