We are pleased to announce some updates to the testing being offered through Genome-wide Sequencing Ontario (GSO):
Type of genome-wide sequencing:
Since January 2026 we have been working to transition the majority of cases to genome sequencing (GS), rather than exome sequencing. GSO will be providing exclusively genome sequencing moving forwards. While GS does include copy number variant analysis, microarray could still be considered when clinically warranted.
Reported variant types:
From July 2026 onward, our GS analysis will include analysis of mitochondrial DNA variants, as well as screening for the following select repeat expansion disorders: FMR1 disorders, Friedreich ataxia, myotonic dystrophy type 1, and spinal and bulbar muscular atrophy.
Please note:
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Short read GS cannot accurately determine the size of expanded alleles; when applicable, the report will indicate the possible presence of expanded alleles and recommend targeted diagnostic testing for confirmation and determination of repeat size.
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Short read GS is not optimized to detect large mtDNA deletions; if a mitochondrial DNA condition is strongly suspected, consider ordering targeted testing for these conditions.
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GSO does not have the capacity to re-analyze previously reported cases specifically for analysis of mtDNA or screening of repeat expansion disorders; if testing for those is clinically indicated, please order testing at the appropriate laboratory.
As always, the specific methodology used and types of variants included in analysis of a case are detailed in the report. Any questions about a specific case can be directed towards the interpreting laboratory. We continue to work hard to bring turnaround times back within target, and appreciate your patience.