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. 2020 Jan 14;94(2):e200–e204. doi: 10.1212/WNL.0000000000008734

Figure. Catecholamine biosynthesis and plasma levels in normal controls and patients with congenital deficiency of cytochrome b561 (CYB561) and dopamine β-hydroxylase (DBH) deficiencies.

Figure

(A) Catecholamine biosynthesis with the conversion of DOPA to dopamine (DA) through l-aromatic amino acid decarboxylase (AAAD), to norepinephrine (NEpi) through DBH, to epinephrine (Epi) through phenylethanolamine N-methyltransferase (PNMT), and the intraneuronal metabolites of dopamine (3,4-dihydroxyphenylacetic acid [DOPAC]) and norepinephrine (3,4-dihydroxyphenylglycol [DHPG]). Cytochrome 561 generates ascorbic acid, a cofactor in the function of DBH. NEpi can also be produced therapeutically from droxidopa via AAAD, bypassing the enzymatic defect. (B) Plasma levels of NEpi, Epi, and DA in normal controls, patients with DBH deficiency, and patients 1, 2, and 4 with CYB561 deficiency. (C) Plasma levels of the intraneuronal metabolites DHPG and DOPAC and of DOPA.