This study was motivated by the observations of the presence in DIPG patients of ACVR1 heterozygous mutations (~25% frequency) that are strongly correlated with the H3.1K27M mutation5,14,15 and the contrasting prognosis statistics showing either the same or longer survival time of DIPG patients harboring tumors with ACVR1 mutations2,16. The gene discussed is ACVR1; the disease is diffuse intrinsic pontine glioma.