SERPINE1 and avascular necrosis: The incidence of AVN in children and adolescents who undergo chemotherapy for ALL varies from 2.3% to 7.7%.3-6 Median age at diagnosis of AVN was 13.5 years in one study.7 Median time from diagnosis to the development of AVN after chemotherapy is 1.14 years (range, 0.25 years to 2.12 years).4,5 Whereas the etiology of AVN is multifactorial, independent risk factors that have been found to be associated with the development of AVN are female sex,7 high body mass index,8 PAI-1 (SERPINE1) genetic variation,9 lower albumin,10 high cholesterol and lipid levels,10,11 and genomic variation.10,12