['Epidemiological evidence has suggested that some childhood acute lymphoblastic leukemia (ALL) may be initiated in utero and may have an infectious etiology. The human polyomavirus JC virus (JCV) has been discussed as a candidate virus, but its presence has not been demonstrated in leukemia cells from children with ALL. The aim of this study was, therefore, to investigate if prenatal human polyomavirus infection could still indirectly be correlated to the development of childhood ALL.', 'Fifty-four Guthrie cards (stored, dried blood spots filter papers, routinely collected from newborns for different screening analyses), collected at 3-5 days of age, from Swedish children who subsequently developed ALL, as well as from 37 healthy controls, were investigated by nested PCR for the presence of human polyomaviruses JCV and BK virus (BKV).', 'JCV and BKV DNA were not detected in any of the Guthrie cards from ALL patients or from healthy controls, although all tested samples had amplifiable DNA as confirmed by an HLA DQ PCR.'] Is human polyomavirus DNA detected in Guthrie cards ( dried blood spots ) from children who developed acute lymphoblastic leukemia?