GNAL and Huntington disease: GNAL, which is highly expressed in the basal ganglia, plays an important role in MSN dopamine signalling.45,70 Reduced levels of GNAL have been reported in the caudate and putamen of HD patients.44,45 We found GNAL to be significantly elevated in the CSF of HD mutation carriers compared with controls (P = 0.043), which could reflect an increased release from degenerating striatal MSNs.