CDKN2B and acute lymphoblastic leukemia: In hyperdiploid ALL forms, these changes consist of an acquired homozygosity of the complete or at least the relevant parts of chromosome 9 (Morison et al., 2002; Safavi et al., 2013; Lundin et al., 2016), which commonly concurs with a heterozygous deletion of both CDKN2A and CDKN2B or a homozygous deletion of CDKN2A alone (Mullighan et al., 2007; Safavi et al., 2013).