Key result
A novel genome sequencing-based SMN copy-number caller achieved 99.8% agreement for SMN1 and 99.7% for SMN2 compared to orthogonal methods, with 100% precision for both SMA and carriers.
Why the study?
Analysis of the SMN1 region is challenging due to near-identical sequences with SMN2, while population-wide SMA screening to quantify SMN1 copy number is recommended.
Does a novel genome sequencing-based method accurately identify SMN1 and SMN2 copy numbers for SMA diagnosis and carrier screening?
Observational (n=12,747)
Yes
Does a novel genome sequencing-based method accurately identify SMN1 and SMN2 copy numbers for SMA diagnosis and carrier screening?
A novel genome sequencing-based method accurately identifies SMN1 and SMN2 copy numbers, enabling comprehensive SMA testing and carrier screening.
Answers are grounded in this paper and cite their sources.
GS-based SMN1 CN detection may aid SMA screening; leaves open large-scale validation before clinical adoption.
PURPOSE: Spinal muscular atrophy (SMA), caused by loss of the SMN1 gene, is a leading cause of early childhood death. Due to the near identical sequences of SMN1 and SMN2, analysis of this region is challenging. Population-wide SMA screening to quantify the SMN1 copy number (CN) is recommended by the American College of Medical Genetics and Genomics. METHODS: We developed a method that accurately identifies the CN of SMN1 and SMN2 using genome sequencing (GS) data by analyzing read depth and eight informative reference genome differences between SMN1/2. RESULTS: We characterized SMN1/2 in 12,747 genomes, identified 1568 samples with SMN1 gains or losses and 6615 samples with SMN2 gains or losses, and calculated a pan-ethnic carrier frequency of 2%, consistent with previous studies. Additionally, 99.8% of our SMN1 and 99.7% of SMN2 CN calls agreed with orthogonal methods, with a recall of 100% for SMA and 97.8% for carriers, and a precision of 100% for both SMA and carriers. CONCLUSION: This SMN copy-number caller can be used to identify both carrier and affected status of SMA, enabling SMA testing to be offered as a comprehensive test in neonatal care and an accurate carrier screening tool in GS sequencing projects.
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Chen et al. (2020) conducted an observational in Spinal muscular atrophy (n=12,747). Genome sequencing-based SMN copy-number caller vs. Orthogonal methods (digital PCR, MLPA) was evaluated on Agreement of SMN1 copy number calls with orthogonal methods. A novel genome sequencing-based SMN copy-number caller achieved 99.8% agreement for SMN1 and 99.7% for SMN2 compared to orthogonal methods, with 100% precision for both SMA and carriers.
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