Extraction of RNA from Dried Blood on Filter Papers after Long-Term Storage

Blood dried on filter paper is widely used for screening of inherited metabolic disorders (1). In Sweden, such filters from all newborns have been permanently stored since 1975. It has been shown that proteins and DNA may be recovered from these cards after extended periods of storage (2)(3)(4). RNA, however, has been considered too vulnerable to degradation by ribonucleases to be recovered from these filters. Despite this, Zhang and McCabe (5) and Matsubara et al.(6) reported that mRNA could be isolated from such filters after up to 4 years of storage. The stability of viral RNA on filters has also been reported (7)(8), although this was not tested over extended periods of time. The purpose of the present study was to investigate whether RNA could be recovered from filters that had been stored since 1975 and be amplified by reverse transcription-PCR. After approval by the local ethics committee, we randomly selected filter papers (specimen collection paper 2992; Schleicher & Schuell) that had been stored for 1 month, 21 years, and 27 years; for each time point, we selected five filters. One-fourth of a spot (∼0.3 cm2) containing dried blood was cut out of each filter with a sterile razor …