HTT and Huntington disease: Interestingly, decreased levels of BDNF are reported in the striatum, cortex, and brainstem of HD patients.21 A deficient cortical transcription of the BDNF gene, its defective transport to the striatum and a reduced level of mRNA coding TrkB in the caudate nucleus have been also shown.21 Moreover, the accumulation of mutated huntingtin may be toxic to cardiomyocytes in humans, as showed in mouse models that developed cardiac dysfunction progressing to severe failure over a few weeks.22