PTPN11 and neuroblastoma: Among successful utilization of WES to identify mutations in NB, a recent paper by Pugh et al. described genetic variations of 240 high-risk NB specimens, and identified genes with significant somatic mutation frequencies (mutation frequencies of < 9.2%) including ALK, PTPN11, ATRX, MYCN and NRAS which percentages regarded as too low to be identified in a study in which fewer than hundreds of tumors were analyzed14,26,56,57.