NF1 and neoplasm: In addition, it remained elusive if the two NF1 mutations detected in the tumor of patient #2 after ALK inhibitor treatment occurred in two separate clones or in one clone, and in the latter case if these mutations occurred in cis or in trans. It will be important to extend these findings to prospective studies, which will enable measurements of mutation incidence and a more detailed analysis of NF1 alterations.