TP53 is a well known tumor suppressor gene that is mutated in wide variety of cancers. Among cases of acute lymphoblastic leukemia, overall TP53 mutations are reported to occur in less than 10% of cases. However, TP53 mutations have a very high prevalence (approximately 90%) among cases of ALL with low hypodiploid karyotype and in this setting are often associated with monosomy 17 and may be associated with germline TP53 mutations in a significant proportion of such cases in children.