CatReader’s review of The Dressmaker's Mirror: Sudden Death, Genetics, and a Jewish Family's Secret > Likes and Comments
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Just to clarify: clinical genetics labs sequence each base many times (often 20–30× or more), and important variants are usually double-checked by another method before results are reported. The individual results aren't reported they are all just lumped together and reported as a single sequence result. In research labs we don't sequence each base that many times.
Susan wrote: "Just to clarify: clinical genetics labs sequence each base many times (often 20–30× or more), and important variants are usually double-checked by another method before results are reported. The in..."
Hi Susan, just seeing this now - I think we are talking about the same thing, but just in different terms. Most clinical labs do germline sequencing via NGS or even long read sequencing these days, where coverages of at least 100-200x for whole exome is the bare minimum -- the 20-30x you're referring to is probably Sanger which isn't done a ton these days. But regardless of the coverage, the benchwork for the DNA extraction, PCR amplification, and sequencing readout is only done once presuming all quality metrics pass, not many times. It's rare for a sequencing result to have to be double-checked by an orthogonal method; that would really only apply to the limitations of a method like short-read sequencing (aka NGS) where large deletions and insertions aren't adequately parseable -- then it's useful to do long-read sequencing or a fragment analysis technique.
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Susan
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Oct 02, 2025 11:14PM
Just to clarify: clinical genetics labs sequence each base many times (often 20–30× or more), and important variants are usually double-checked by another method before results are reported. The individual results aren't reported they are all just lumped together and reported as a single sequence result. In research labs we don't sequence each base that many times.
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Susan wrote: "Just to clarify: clinical genetics labs sequence each base many times (often 20–30× or more), and important variants are usually double-checked by another method before results are reported. The in..."Hi Susan, just seeing this now - I think we are talking about the same thing, but just in different terms. Most clinical labs do germline sequencing via NGS or even long read sequencing these days, where coverages of at least 100-200x for whole exome is the bare minimum -- the 20-30x you're referring to is probably Sanger which isn't done a ton these days. But regardless of the coverage, the benchwork for the DNA extraction, PCR amplification, and sequencing readout is only done once presuming all quality metrics pass, not many times. It's rare for a sequencing result to have to be double-checked by an orthogonal method; that would really only apply to the limitations of a method like short-read sequencing (aka NGS) where large deletions and insertions aren't adequately parseable -- then it's useful to do long-read sequencing or a fragment analysis technique.
