BDNF and Huntington disease: Consistently, in the HD patient iPS-derived striatal neurons, knocking-down Gpr52 suppresses the mHtt-dependent neuronal loss and caspase 3 activation induced by withdrawn of the brain-derived neurotrophic factor (BDNF) (HD iPS Consortium, 2012; Lu and Palacino, 2013) (Figure 5B–C).