ACVR1 and diffuse intrinsic pontine glioma: Approximately 20% of DIPG cases harbor recurrent ACVR1 mutations co-occurred with H3.1K27M, which encode the BMP type I receptor, also known as ALK2 (Bocciardi et al. 2009; Buczkowicz et al. 2014; Fontebasso et al. 2014; Taylor et al. 2014a, b; Wu et al. 2014).