The efficacy of the mTOR inhibitor sirolimus for the treatment of slow-flow vascular malformations was prospectively evaluated in a small number of phase II trials, all having inherent limitations in terms of patient number, patient population (mostly children, vascular malformation types, absence of genomic studies), and design (undefined treatment time duration versus 12 months) (15, 20–23). The gene discussed is MTOR; the disease is vascular malformation.