In severe SMA mouse models that express little to no SMN, there is evidence for a microvasculopathy involving defective angiogenesis and blood vessel formation that results in systemic manifestations (Hamilton and Gillingwater, 2013; Nash et al, 2016; Wirth, 2021; Wirth et al, 2020). The gene discussed is SMN1; the disease is proximal spinal muscular atrophy.