Effect of unnatural noradrenaline precursor on sympathetic control and orthostatic hypotension in dopamine-beta-hydroxylase deficiency.

A patient with severe orthostatic hypotension due to dopamine-beta-hydroxylase deficiency was treated with the unnatural aminoacid D,L-threo-3,4-dihydroxyphenylserine (DOPS) in the hope that it would serve as a substrate of aromatic-L-aminoacid decarboxylase to produce (-)-noradrenaline. With a dose of 500 mg twice daily by mouth, blood pressure rose gradually from 100/55 to 145/85 mm Hg, and orthostatic hypotension disappeared. After 4 months' treatment the patient is free of symptoms and able to live a normal life. DOPS switched on the production of noradrenaline and reduced the excessive production of dopamine. During treatment plasma noradrenaline rose normally after standing and after infusion of tyramine, a biogenic amine that liberates stored neurotransmitter from sympathetic nerve terminals. These data demonstrate that in congenital dopamine-beta-hydroxylase deficiency dopamine instead of noradrenaline is released as the sympathetic neurotransmitter but that the integrity of the sympathetic neuron is otherwise intact.