DOPAMINE UPTAKE BY PLATELET STORAGE GRANULES IN FIRST-DEGREE RELATIVES OF TOURETTES-SYNDROME PATIENTS

Background: Considering that platelets have been established to be goo d peripheral markers for the study of catecholaminergic neurons, we ha ve applied an assay to measure the uptake of (H-3)-dopamine (DA) into platelet storage granules (PSG). Recently: we reported that Tourette's syndrome (TS) patients (pts) show decreased DA uptake into PSG. Metho ds: In die present study, 28 first-degree relatives (3 with chronic mo tor ties, 3 with transient ties, 6 with obsessive-compulsive behavior and 16 without symptom-atology) belonging to the families of 13 patien ts, and 14 unrelated healthy controls,were studied. Results: Double re ciprocal plots were constructed for each subject, and the apparent max imum velocity (Vmax) and Michaelis constant (Km) were determined by li near regression analysis (Lineaweaver-Burke plots). The uptake of DA ( 0.5-5 mu mol/L) (mean +/- SEM) by PSG from relatives with symptomatolo gy was similar to the TS patients (symptomatic relatives Vmax 181 +/- 22.2 fmol/mg protein, Km (mu mol/L) 6.42 +/- 0.29; TS pts Vmax 108 +/- 69, Km 7.79 +/- 0.64). Relatives without symptomatology on the contra ry showed DA affinity characteristics similar to the cona ols (t test, paired t test, multivariate analysis of variance, and log transformat ion). Conclusions: The data presented suggest that TS is hereditary, b ut they do not distinguish between an autosomal dominant inheritance a nd a mixed or polygenic model. (C) 1998 Society of Biological Psychiat ry.