In MJD, expanded ataxin-3 expression and resulting neuropathology, including autophagy impairments, mitochondria dysfunction, transcriptional dysregulation and others, may influence BBB indirectly, by interfering with the neurovascular coupling, pointing to the need to evaluate other components of the neurovascular unit, such as pericytes. The gene discussed is ATXN3; the disease is Machado-Joseph disease.