The literature being limited to one previous study of nine singletons (Wiemels et al, 1999a), we therefore found it of interest to study the foetal origin of t(12;21) B-precursor ALL by analysing peri-natally obtained blood samples (Guthrie cards) for the presence of TEL-AML1 fusion genes in a series of patients diagnosed with this specific leukaemia subtype. Here, ETV6 is linked to leukemia.