Guthrie cards derived from the New York State Newborn Screening Program were utilized to develop a rapid, economical method for amplifying multiple genes to detect mutations that impact public health. These specimens are untraceable to the donor because identifiers are removed and discarded; therefore, these pilot studies were carried out anonymously. The sample preparation requires minimal manipulation, is amenable to automation, and is useful in laboratories which routinely process large numbers of samples, such as those in typical newborn screening laboratories. Multiple gene fragments may be amplified from a 1 mm punch which contains less than 1 microl of whole blood. The blood spots used in these studies contain sufficient material for up to 25 amplification reactions which multiplex at least four different gene fragments each. Since sufficient material remains on the card after the routine testing is complete, this simple assay can greatly expand the efficacy of current newborn screening programs by permitting DNA diagnosis of some disorders when indicated, particularly those in which genotype-phenotype correlations are useful. In addition to newborn screening specimens, this method is also applicable to whole blood from adults after phlebotomy and from lymphoblastoid cell lines. Use of filter paper for DNA analysis is particularly useful for shipped specimens or for population studies whose subjects are refractory to phlebotomy.