We do agree that in certain circumstances, such as with a positive H3K27M stain or a positive triple-mutated IDH1-mutant/ATRX-lost/p53-mutant tumor, the immunoprofile can very quickly yield a definitive diagnosis; however, it is not clear that there is a clinically significant benefit to having this diagnosis in 2–3 days (IHC) versus 7–10 days (expedited NGS) versus 10–21 days (routine TAT for NGS at our institution) to merit routine use. The gene discussed is IDH1; the disease is neoplasm.