Performance of cellulose-based card for direct genetic testing of spinal muscular atrophy

Spinal muscular atrophy (SMA) is a devastating neuromuscular condition resulting from the loss of the survival motor neuron 1 (SMN1) gene. Precise genetic testing has become essential after the authorization of several potent medications. To achieve this objective, the use of dried blood spot (DBS) has assured convenient and extensive testing from a distance. Nevertheless, developing countries such as Indonesia sometimes lack access to standard filter papers like FTA or Guthrie cards for DBS processing. Here, we aim to develop a cellulose-based card as an alternative filter paper for DBS preparation suitable for the genetic testing of SMA including but not limited to a direct polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and multiplex allele-specific amplification (multi-ASA).

An in-house paper was developed from a 180 gsm cellulose-based paper and was used for DBS preparation. The performance of dried blood spotted on the cellulose-based card (DBSc) was compared to pure genomic DNA (gDNA) isolate and dried blood spotted on FTA cards (DBSf) for genetic testing. The results of the genetic testing of our cellulose-based card were completely matched with those of gDNA and DBSf in both direct PCR-RFLP and Multi-ASA to separate SMN1 from SMN2. In addition, after three months of storing, the DBSc continued to exhibit a clear result, suggesting its high stability for DNA storage.

Our cellulose-based card has the potential to be used for DBS carrier and for further genetic testing using PCR. Our findings can assist physicians in sending DBS samples from SMA suspicion cases to genetic testing centers, thereby preventing diagnosis delay or misdiagnosis.