PHOX2B and Nijmegen breakage syndrome: A study by van Limpt et al.16have described several different frameshift mutations of PHOX2B, such as 284‐291del8nt, 633‐670del38nt, 702‐714dup13nt, 721‐755del35nt, 721‐737dup17nt, and 721‐740del20nt in sporadic NBs. A study by Raabe et al.189has described point mutations such as c.667G>C in a human NB‐derived cell line and c.299G>T in sporadic NB with multifocal primaries, as well as frameshift mutations (c.676delG and c.691_698dup8) in hereditary NB. Mutation of PHOX2B is correlated to RAS‐MAPK pathway activation in NB cell lines.130