Congenital dopamine-beta-hydroxylase deficiency in humans.

Dopamine-beta-hydroxylase (DbetaH) deficiency is a rare autosomal dominant disorder. Due to the absence of DbetaH, there is a blocked conversion of dopamine into norepinephrine. The biochemical hallmark of this syndrome consists of a complete absence of plasma norepinephrine and epinephrine levels in conjunction with an increased plasma dopamine level. Several mutations in the gene that encodes for DbetaH have been described. Up to now, worldwide, 12 patients have been reported. The most important clinical feature is a severe orthostatic hypotension. In addition, several other clinical features like blepharoptosis, hyperflexible joints, high palate, sluggish deep tendon reflexes, and a mild normocytic anemia have been described. The only effective treatment of DbetaH deficiency is L-threo-3,4-dihydroxyphenylserine (DOPS). DOPS is converted directly into norepinephrine. Treatment with DOPS results in a sustained relief of orthostatic symptoms.