Background: Considering that platelets have been established to be good peripheral markers for the study of catecholaminergic neurons, we have applied an assay to measure the uptake of (3H)-dopamine (DA) into platelet storage granules (PSG). Recently, we reported that Tourette's syndrome (TS) patients (pts) show decreased DA uptake into PSG. Methods: In the present study, 28 first-degree relatives (3 with chronic motor tics, 3 with transient tics, 6 with obsessive-compulsive behavior, and 16 without symptomatology) belonging to the families of 13 patients, and 14 unrelated healthy controls were studied. Results: Double reciprocal plots were constructed for each subject, and the apparent maximum velocity (Vmax) and Michaelis constant (Km) were determined by linear regression analysis (Lineaweaver-Burke plots). The uptake of DA (0.5-5 μmol/L) (mean ± SEM) by PSG from relatives with symptomatology was similar to the TS patients (symptomatic relatives Vmax 181 ± 22.2 fmol/mg protein, Km (μmol/L) 6.42 ± 0.29; TS pts Vmax 108 ± 6.9, Km 7.79 ± 0.64). Relatives without symptomatology on the contrary showed DA affinity characteristics similar to the controls (t test, paired t test, multivariate analysis of variance, and log transformation). Conclusions: The data presented suggest that TS is hereditary, but they do not distinguish between an autosomal dominant inheritance and a mixed or polygenic model.
- Platelet vesicles
- Tourette's syndrome