CDK4 and neoplasm: The most common recurrent alterations present at diagnosis, also designated as ‘secondary major alterations’, were mostly mutually exclusive: CDKN2A/2B alterations (5/18, 28%, 4 homozygous deletions, 1 non-sense mutation associated with loss of heterozygozity), MYCN alterations, (4/18, 22%, 2 amplifications, 2 missense mutations), and CDK4 amplifications (3/18, 17%, coamplified with GLI1 in 2 tumors and MDM2 in 1 tumor at 12q13-15 locus).