RASSF1A methylation may have two biological roles in neuroblastoma tumorigenesis depending on the ploidy status and age of patients.

RASSF1A methylation was frequent in neuroblastomas found in infants by mass-screening or infants and children diagnosed clinically, whereas CASP8 and DCR2 methylation was only frequent in tumors in children. When classified according to the ploidy status, RASSF1A and PCDHB methylation was only associated with MYCN amplification and poor outcomes in infants with a clinically diagnosed diploid, not triploid tumor. RASSF1A and PCDHB methylation was associated with poor outcomes in children with triploid and diploid tumors, respectively, and with MYCN amplification in children with diploid tumor. RASSF1A methylation may have two biological roles based on the ploidy status and patient's age.