Like most of the other 1p36 tumor suppressor genes identified, somatically acquired CHD5 mutations are rare in primary NBs, however methylation of the CHD5 promoter is a common event in the high-risk tumors as well as NB cell lines, and it is generally associated with both 1p deletion and MYCN amplification [105,106]. This evidence concerns the gene CHD5 and Nijmegen breakage syndrome.