Plasma Catechols in Familial Dysautonomia: A Long-term Follow-up Study

Abstract

This study tested whether familial dysautonomia (FD) involves progressive loss of noradrenergic nerves. Plasma levels of catechols, including dihydroxyphenylglycol (DHPG), norepinephrine (NE), dopamine (DA), and DOPA, were measured in 7 adult patients with FD and 50 healthy control subjects. FD patients were re-tested after a mean follow-up period of 13 years. Compared to controls, FD patients had low plasma levels of DHPG (P < 0.001), high DOPA and DA levels (P = 0.01, P = 0.0002), and high NE:DHPG (P < 0.0001), DA:NE (P = 0.0003), and DOPA:DHPG (P < 0.0001) ratios. At follow-up there were no changes in plasma levels of individual catechols; however, there were further increases in DOPA:DHPG ratios (mean 24 +/- 7%, P = 0.01). In FD, plasma catechol profiles are sufficiently stable, at least over a decade, to be used as a biomarker of disease involvement. An increasing DOPA:DHPG ratio suggests slight but consistent, progressive loss of noradrenergic neurons.