MYCN and neuroblastoma: The International Neuroblastoma Risk Group (INRG) classification system was developed to categorize neuroblastoma cases into three groups, high, intermediate, and low risk, according to the prognostic variables: stage, age at diagnosis, MYCN oncogene status, chromosome 11q status, DNA ploidy, and the histologic category and grade of tumor differentiation based on the International Neuroblastoma Pathology Classification (INPC) [2].