Objective:To assess the effectiveness and feasibility of carrier detection for Spinal muscular atrophy (SMA) by using digital PCR assay.Methods:Peripheral blood samples were collected from 214 pregnant women who were routinely screened for SMA carriers, of which 204 were randomly selected samples and 10 were samples with known copy numbers of SMN1 exons 7 and 8. Samples with known copy numbers of SMN1 exons 7 and 8 were randomly mixed into the experiment to validate the performance of the digital PCR assay. The copy numbers of SMN1 exons 7 and 8 and SMN2 exons 7 and 8 in peripheral blood samples were detected by digital PCR assay. The results of SMN1 exons 7 and 8 were compared with those of the quantitative PCR method to assess the reliability and clinical performance of the digital PCR assay. Results:Among the 204 random samples, digital PCR has detected five samples with simultaneous heterozygous deletion of SMN1 exons 7 and 8, three samples with heterozygous deletion of SMN1 exon 8 only, and 196 samples with no deletion of SMN1 exons 7 and 8. Ten samples with known SMN1 exons 7 and 8 copy numbers were detected with the expected values. The digital PCR test results were fully consistent with that of the quantitative PCR. Conclusion:The results of digital PCR for the detection of copy number variation of SMN1 exons 7 and 8 were consistent with qPCR. Digital PCR assay was able to clearly distinguish the copy number of the target genes, therefore can be used for SMA carrier screening. Moreover, it can also detect copy number of SMN2 exons 7 and 8, which can provide more information for genetic counseling.

Objective:This study aims to evaluate the performance of digital PCR (dPCR) detecting multiple and single copies genes of the Epstein-Barr virus (EBV) for nucleic acid quantification and explore their applicability in clinical settings.Methods:Compared the sensitivity, specificity, precision, lower limit of detection (LoD), and linearity for multicopy BamHI-W dPCR and single-copy EBNA1 dPCR systems. Linear regression analysis using the least squares method was employed to evaluate the linearity. Additionally, we analyzed plasma samples from 182 patients with suspected EBV-related diseases between January and July 2022 at the Southern Medical University Southern Hospital, using both dPCR and quantitative PCR (qPCR) for EBV DNA quantification. Linear regression analysis using the least squares method was conducted to assess their quantitative correlation.Results:The dPCR systems for both multicopy and single-copy genes showed excellent linearity ( R 2 values of 0.992 and 0.997, respectively, both P<0.001). The LoD were 188 IU/ml for BamHI-W gene and 358 IU/ml for EBNA1 gene dPCR systems. The logarithmic coefficient of variation ( CV) values for high-concentration samples (1 000 000 IU/ml) were 0.34% and 0.21% for the BamHI-W gene and EBNA1 gene dPCR assays, respectively, while for low-concentration samples (5 000 IU/ml) were 0.98% and 0.64%, respectively. In the detection of seven common clinical infectious pathogens and EBV positive samples, only EBV-positive samples yielded positive signals in the dPCR detection system, with no cross-reaction with other pathogens. In 182 samples, the positive detection rates were 47.80% (87/182) for BamHI-W gene and 35.16% (64/182) for EBNA1 gene dPCR, compared to 43.41% (79/182) for qPCR. Linear correlation analysis with qPCR showed R2 values of 0.837 for BamHI-W gene and 0.763 for EBNA1 gene dPCR (both P<0.001). The BamHI-W gene copy number ranged from 3 to 18 copies per clinical sample, with patient-specific variations. There was a high consistency in viral load trends between the multicopy BamHI-W gene and single-copy EBNA1 gene dPCR systems within individual patients. Conclusions:The dPCR methods detecting EBV multiple and single copies genes showed high sensitivity, specificity, precision, and quantitative accuracy, suitable for clinical sample analysis. The multicopy BamHI-W gene dPCR method notably enhances detection sensitivity and can be used as a supplement to current EBV DNA load detection methods, especially in low-concentration samples. For within-patient EBV DNA monitoring, the multicopy gene method proves more effective, while inter-patient comparisons might necessitate single-copy gene methods or normalize them using the same standard.