The strengths of our study include the use of DBS samples for a large number of newborns with and without DS, the availability of both gestational age and age at DBS collection that enabled us to calculate chronological age from conception, and the inclusion of DS‐ALL cases and GATA1 mutation data that allowed us to explore the association between epigenetic age and hematological phenotypes in DS. The gene discussed is GATA1; the disease is acute lymphoblastic leukemia.