Neuroblastoma is the most common childhood cancer diagnosed before the age of 1 year, and accounts for 10 to 15% of all cancer deaths in children. Some patients inherit a genetic predisposition to neuroblastoma due to germline mutations, whereas others develop sporadic disease that may result from either germline or somatic mutations. Neuroblastoma tumors are derived from embryonic cells that form the primitive neural crest and give rise to the adrenal medulla and the sympathetic nervous system. Histopathologically, neuroblastoma can range in type from the most aggressive form, neuroblastoma, composed entirely of immature neural precursor cells, to ganglioneuroma, composed entirely of mature neural tissue. The most important prognostic factor for patients with neuroblastoma is the extent of the tumor at the time of diagnosis. Neuroblastoma can also be part of cancer-prone syndromes, such as paragangliomas. Genetic Heterogeneity of Susceptibility to Neuroblastoma Susceptibility to neuroblastoma is genetically heterogeneous and is conferred by mutation in the PHOX2B gene on chromosome 4p12 and by mutation in the ALK gene on chromosome 2p23. Loci implicated in the development of neuroblastoma include 6p, 2q35, and 1q21. [From OMIM]