Fig. 5
From: A feasibility study for the newborn screening of spinal muscular atrophy
The proposed two-tiered strategy for newborn screening of spinal muscular atrophy (SMA) using DNA as a testing substrate at both levels. All blood spots would undergo extraction and first-tier analysis with the real-time polymerase chain reaction (PCR) protocol outlined in this report. A positive result from the first tier would trigger the collection of a recall sample of whole blood through the individual's primary care physician and subsequent analysis using the competitive PCR methodology currently used for SMA molecular analysis. This procedure would both confirm the homozygous deletion in SMN1 and quantify SMN2 gene copy numbers. Recall samples not confirming a positive result from the first tier would be reanalyzed to confirm the negative result using the competitive PCR.
