ACVR1 and neoplasm: Furthermore, Pan et al. [64] isolated the circulating tumour DNA from the CSF of brainstem gliomas (n = 57, of which 23 samples were diffuse midline glioma), which led to the detection of multiple tumour-specific mutations, including H3F3A, TP53, ATRX, PDGFRA, HIST1H3B, FAT1, PPM1D, ACVR1, NF1, IDH1 and PIK3CA. With respect to the sensitivity of mutation detection, CSF-circulating tumour DNA gave rise to a higher sensitivity (100%) as compared to plasma-circulating tumour DNA (38%) [64].