Reduced striatal D-2 receptor binding in myoclonus-dystonia

Purpose To study striatal dopamine D-2 receptor availability in DYT11 mutation carriers of the autosomal dominantly inherited disorder myoclonus-dystonia (M-D). Methods Fifteen DYT11 mutation carriers ( 11 clinically affected) and 15 age- and sex-matched controls were studied using I-123-IBZM SPECT. Specific striatal binding ratios were calculated using standard templates for striatum and occipital areas. Results Multivariate analysis with corrections for ageing and smoking showed significantly lower specific striatal to occipital IBZM uptake ratios (SORs) both in the left and right striatum in clinically affected patients and also in all DYT11 mutation carriers compared to control subjects. Conclusions Our findings are consistent with the theory of reduced dopamine D-2 receptor (D2R) availability in dystonia, although the possibility of increased endogenous dopamine, and consequently, competitive D2R occupancy cannot be ruled out