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Practice guideline: joint CCMG-SOGC recommendations for the use of chromosomal microarray analysis for prenatal diagnosis and assessment of fetal loss in Canada
  1. Christine M Armour1,
  2. Shelley Danielle Dougan2,
  3. Jo-Ann Brock3,4,
  4. Radha Chari5,
  5. Bernie N Chodirker6,7,
  6. Isabelle DeBie8,
  7. Jane A Evans7,
  8. William T Gibson9,10,
  9. Elena Kolomietz11,
  10. Tanya N Nelson9,12,13,
  11. Frédérique Tihy14,
  12. Mary Ann Thomas15,16,
  13. Dimitri J Stavropoulos17
  14. On-Behalf-Of the Canadian College of Medical Geneticists
  1. 1 Department of Genetics, Children’s Hospital of Eastern and Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
  2. 2 BORN Ontario, Children’s Hospital of Eastern Ontario, Ottawa, Ontario, Canada
  3. 3 Departments of Obstetrics and Gynecology, Dalhousie University Medical School, Halifax, Nova Scotia, Canada
  4. 4 Department of Laboratory Medicine, Dalhousie University Medical School, Halifax, Nova Scotia, Canada
  5. 5 Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada
  6. 6 Department of Pediatrics and Child Health, Max Rady College of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
  7. 7 Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
  8. 8 Department of Medical Genetics and Core Molecular Diagnostic Laboratory, McGill University Health Centre, McGill University, Montreal, Quebec, Canada
  9. 9 Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
  10. 10 Department of Medical Genetics, BC Children’s Hospital Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
  11. 11 Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
  12. 12 Department of Pathology and Laboratory Medicine, BC Children’s and BC Women’s Hospitals, Vancouver, British Columbia, Canada
  13. 13 Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
  14. 14 Service de Génétique Médicale, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
  15. 15 Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
  16. 16 Alberta Children’s Hospital Research Institute for Child and Maternal Health, University of Calgary, Calgary, Alberta, Canada
  17. 17 Genome Diagnostics, Department of Pediatric Laboratory Medicine, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
  1. Correspondence to Dr Christine M Armour, Department of Genetics, Children’s Hospital of Eastern Ontario, Ottawa, Canada; carmour{at}cheo.on.ca

Abstract

Background The aim of this guideline is to provide updated recommendations for Canadian genetic counsellors, medical geneticists, maternal fetal medicine specialists, clinical laboratory geneticists and other practitioners regarding the use of chromosomal microarray analysis (CMA) for prenatal diagnosis. This guideline replaces the 2011 Society of Obstetricians and Gynaecologists of Canada (SOGC)-Canadian College of Medical Geneticists (CCMG) Joint Technical Update.

Methods A multidisciplinary group consisting of medical geneticists, genetic counsellors, maternal fetal medicine specialists and clinical laboratory geneticists was assembled to review existing literature and guidelines for use of CMA in prenatal care and to make recommendations relevant to the Canadian context. The statement was circulated for comment to the CCMG membership-at-large for feedback and, following incorporation of feedback, was approved by the CCMG Board of Directors on 5 June 2017 and the SOGC Board of Directors on 19 June 2017.

Results and conclusions Recommendations include but are not limited to: (1) CMA should be offered following a normal rapid aneuploidy screen when multiple fetal malformations are detected (II-1A) or for nuchal translucency (NT) ≥3.5 mm (II-2B) (recommendation 1); (2) a professional with expertise in prenatal chromosomal microarray analysis should provide genetic counselling to obtain informed consent, discuss the limitations of the methodology, obtain the parental decisions for return of incidental findings (II-2A) (recommendation 4) and provide post-test counselling for reporting of test results (III-A) (recommendation 9); (3) the resolution of chromosomal microarray analysis should be similar to postnatal microarray platforms to ensure small pathogenic variants are detected. To minimise the reporting of uncertain findings, it is recommended that variants of unknown significance (VOUS) smaller than 500 Kb deletion or 1 Mb duplication not be routinely reported in the prenatal context. Additionally, VOUS above these cut-offs should only be reported if there is significant supporting evidence that deletion or duplication of the region may be pathogenic (III-B) (recommendation 5); (4) secondary findings associated with a medically actionable disorder with childhood onset should be reported, whereas variants associated with adult-onset conditions should not be reported unless requested by the parents or disclosure can prevent serious harm to family members (III-A) (recommendation 8).

The working group recognises that there is variability across Canada in delivery of prenatal testing, and these recommendations were developed to promote consistency and provide a minimum standard for all provinces and territories across the country (recommendation 9).

  • prenatal diagnosis
  • chromosomal microarray
  • guideline

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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Footnotes

  • Contributors CMA, SDD, JAB, RC, BNC, IDB, JAE, WTG, EK, FT, MAT, TNN, and DJS conceived and developed the content. CMA, SDD, RC, IDB, JAE, WTG, EK, FT, MAT, TNN and DJS drafted the initial version. All authors critically revised the article and approved the final version.

  • Funding The authors also acknowledge funding from The Hospital for Sick Children Centre for Genetic Medicine and the University of Toronto McLaughlin Centre.

  • Competing interests None declared.

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

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