Figure 1.

Scheme of the SMN1-deletion detection system using dried blood spots (DBS). Our system consists of two steps. Step (1) targeted pre-amplification of the SMN genes: the target sequences in the SMN genes from DBS are pre-amplified by conventional polymerase chain reaction (PCR), and Step (2) gene-specific amplification of SMN1 and SMN2 exon 7: SMN1 deletion is detected by real-time modified competitive oligonucleotide priming-PCR (mCOP-PCR) with the pre-amplified products. In the first step, a punched circle from each DBS is placed directly into the reaction tube of conventional PCR (direct PCR).