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Leveraging the power of new molecular technologies in the clinical setting requires unprecedented awareness of limitations and drawbacks: experience of one diagnostic laboratory
  1. Landry Nfonsam1,
  2. Shelley Ordorica1,
  3. Mahdi Ghani1,
  4. Ryan Potter1,
  5. Audrey Schaffer1,
  6. Hussein Daoud1,
  7. Nasim Vasli1,
  8. Caitlin Chisholm1,
  9. Elizabeth Sinclair-Bourque1,
  10. Jean McGowan-Jordan1,2,
  11. Amanda C Smith1,2,
  12. Olga Jarinova1,2,
  13. Lucas Bronicki1,2
  1. 1 Department of Genetics, Children’s Hospital of Eastern Ontario, Ottawa, Ontario, Canada
  2. 2 Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada
  1. Correspondence to Dr Landry Nfonsam, Department of Genetics, Children’s Hospital of Eastern Ontario, Ottawa, K1H8L1, Ontario, Canada; LNfonsam{at}


Background Advances in molecular technologies and in-silico variant prediction tools offer wide-ranging opportunities in diagnostic settings, yet they also present with significant limitations.

Objective Here, we contextualise the limitations of next-generation sequencing (NGS), multiplex ligation-dependent probe amplification (MLPA) and in-silico prediction tools routinely used by diagnostic laboratories by reviewing specific experiences from our diagnostic laboratory.

Methods We investigated discordant annotations and/or incorrect variant ‘callings’ in exons of 56 genes constituting our cardiomyopathy and connective tissue disorder NGS panels. Discordant variants and segmental duplications (SD) were queried using the National Center for Biotechnology Information (NCBI) Basic Local Alignment Search Tool and the University of California Santa Cruz genome browser, respectively, to identify regions of high homology. Discrepant variant analyses by in-silico models were re-evaluated using updated file entries.

Results We observed a 5% error rate in MYH7 variant ‘calling’ using MLPA, which resulted from >90% homology of the MYH7 probe-binding site to MYH6. SDs were detected in TTN, PKP2 and MYLK. SDs in MYLK presented the highest risk (15.7%) of incorrect variant ‘calling’. The inaccurate ‘callings’ and discrepant in-silico predictions were resolved following detailed investigation into the source of error.

Conclusion Recognising the limitations described here may help avoid incorrect diagnoses and leverage the power of new molecular technologies in diagnostic settings.

  • diagnostics tests
  • genetic screening/counselling
  • molecular genetics

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  • OJ and LB contributed equally.

  • Contributors LN, OJ, LB, ACS, HD, NV and MG planned the study. SO, RP, HD, NV, MG and LN conducted the experiments. LN, OJ, LB, JM-J, AS, ES-B and CC reported/wrote the article. LN, OJ and LB submitted the study.

  • Funding This study was supported by the Innovation Fund of the Alternative Funding Plan for the Academic Health Sciences Centre of Ontario.

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.