ABSTRACT
Genetic studies have demonstrated chromosomal abnormalities in up to 80% of cases of neuroblastoma. The most important of these are MYCN amplifications, deletions of chromosome 1p and aneuploidy. In most cases, the defect is found to be on chromosomes 1 and 17, the most consistent being a deletion on the short arm of chromosome 1 (1p36.1-1p36.3).63 Additional chromosomal abnormalities have been identified at 4p, 6q, 9q, 10q, 11q, 12q, 13q, 14q, 16q, 22p and 22q.64 Amplification of the N-myc oncogene (usually found on chromosome 2), has been associated with a more advanced form of the malignancy and is a poor prognostic sign.65 Recent reports of the downregulation of activin-A by MYCN offers an explanation for this as deprived neuroblastoma cells experience a decrease in growth-inhibitory signal transduction leading to excessive cell growth.66 It is interesting to note that p53 gene mutations are absent in neuroblastomas67 although they are present in other tumors of childhood.
