The laboratory is developing a faster, easier and cost-effective way to simultaneously screen for both conditions. The test also can be used to assess the severity of SMA.
The approach uses two Quantabio’s DNA testing products — Extracta DBS and PerfeCTa Multiplex qPCR ToughMix — that provide more efficient DNA extraction from dried blood spots and more sensitive detection, compared to conventional methods.
“We make our technology choices based on several criteria, such as ease of use, consistent performance, and compatibility with challenging samples,” Mei Baker, MD, co-director of the Wisconsin’s Newborn Screening Laboratory and professor at University of Wisconsin-Madison said in a press release.
“With Quantabio products, we were able to successfully develop and validate a real‐time multiplex PCR assay that simultaneously screens for SMA and SCID,” Baker said.
Baker developed an innovative DNA extraction technique, now part of Extracta DBS sold by Quantabio, with the intent of processing large amounts of DNA samples — such as those analyzed in public health laboratories — faster and more efficiently. It requires only 30 minutes to extract DNA with enough quality to be used in Sanger sequencing (a more traditional form of DNA sequencing), or next-generation sequencing (NGS), which is a more advanced technique that allows rapid sequencing of large amounts of DNA, even a person’s genome (the whole set of genes).
“Dr. Baker is one of the early pioneers in public health genetics, who is best known for establishing the world’s first Newborn Screening program for SCID,” said Heather Meehan, PhD, vice president and head of Quantabio.
“Extracta DBS now combines her same pioneering extraction technique with our ability to scale production. … This enhancement is another example of our ongoing commitment to improving product performance, accelerating turnaround times, streamlining workflows, and increasing affordability,” Meehan said.
In a recent poster, Wisconsin’s State Lab scientists reported they have minimized the costs of dual screening for SMA and SCID by adding the SMA test to an existing test used to identify SCID in infants. The test uses a technique of DNA amplification and detection called “multiplex real-time PCR.”
In addition, researchers are testing a molecular tool called droplet digital PCR (ddPCR), to screen the number of copies of the SMN2 gene in SMA patients, which can help determine early on the severity of the disease. Some people have extra copies of SMN2, and the number of copies can modify the course of SMA. The more copies there are, the less severe the symptoms tend to be.
“[I]dentifying infants with 2 or 3 SMN2 copies and treating at the earliest possible time point is critical to ensure the best outcomes,” researchers wrote.
“The comprehensive approach of newborn screening for SMA, that includes “just in time” knowledge of SMN2 copy numbers in newborns who have homozygous deletion of exon 7 in SMN1 [the most common cause of SMA], will facilitate early clinical follow‐up, family counseling, and treatment planning,” they concluded.