The Use of Microarrays in the Prenatal and Postnatal Setting – Current Professional Guidelines
Learning Objectives and CME/Disclosure Information
This activity is intended for healthcare providers delivering care to women and their families.
After completing this activity, the participant should be better able to:
1. List the benefits and limitations of microarray technology 2. Discuss professional guidelines on the use of microarrays in the prenatal and postnatal period
Estimated time to complete activity: 0.25 hours
Susan J. Gross, MD, FRCSC, FACOG, FACMG
President and CEO, The ObG Project
Disclosure of Conflicts of Interest
Postgraduate Institute for Medicine (PIM) requires faculty, planners, and others in control of educational content to disclose all their financial relationships with ineligible companies. All identified conflicts of interest (COI) are thoroughly vetted and mitigated according to PIM policy. PIM is committed to providing its learners with high quality accredited continuing education activities and related materials that promote improvements or quality in healthcare and not a specific proprietary business interest of an ineligible company.
The PIM planners and others have nothing to disclose. The OBG Project planners and others have nothing to disclose.
Faculty: Susan J. Gross, MD, receives consulting fees from Cradle Genomics, and has financial interest in The ObG Project, Inc.
Planners and Managers: The PIM planners and managers, Trace Hutchison, PharmD, Samantha Mattiucci, PharmD, CHCP, Judi Smelker-Mitchek, MBA, MSN, RN, and Jan Schultz, MSN, RN, CHCP have nothing to disclose.
Method of Participation and Request for Credit
Fees for participating and receiving CME credit for this activity are as posted on The ObG Project website. During the period from Dec 31 2017 through Jan 25 2023, participants must read the learning objectives and faculty disclosures and study the educational activity.
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Joint Accreditation Statement
In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.
Physician Continuing Medical Education
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Chromosomal microarray (also known as CMA) technology has revolutionized the practice of genetics and is now commonly ordered prenatally and throughout the lifespan. Structural chromosomal anomalies, once too small to be ‘seen’ using conventional karyotyping, can now be detected using molecular techniques. Microarrays can detect copy number variants (CNVs) and therefore identify chromosomal regions where there is excess DNA (a duplication) or missing DNA (a deletion).
Consider the following when counseling:
Benefits of Microarrays
Prenatal detection of clinically significant CNVs that would have been missed using conventional karyotyping alone
6% of abnormal fetuses with a normal karyotype may have pathogenic CNVs or likely pathogenic CNVs
Isolated finding: 5.6%
Multiple anomalies: 9.1%
1.7% of normal fetuses and normal karyotype may have pathogenic CNVs or likely pathogenic CNVs
Postnatal detection of significant CNVs that would have been missed using conventional karyotyping alone
Developmental delay and intellectual disability
An additional 12.2% – 19% pathogenic anomalies May be detected with the addition of microarray
Can be performed on tissue that is no longer viable
If DNA is present and of sufficient quality, test can be run on stillbirth specimens or products of conception
Limitations of Microarrays
Balanced translocations occur in approximately 1/500 individuals and are usually benign
Because there is minimal/no additional or deleted genetic material, balanced translocations will go undetected with microarray but depending on size, may be seen with conventional karyotyping
Serious consequences are still possible with balanced translocations due to breakpoints disrupting genes
ACMG (2018) notes the importance of balanced rearrangements (e.g., translocation, inversion, insertion) and states that “recurrence risk counseling is indicated for offspring of parent with a balanced rearrangement
Estimated additional diagnostic yield of 0.78 to 1.3% if a G-banded karyotype is performed following a negative microarray
Single gene disorders
May be caused by a single or small base pair change and will not be detected on microarray
Variants of uncertain significance (VUS)
Can occur in 1 to 2% of cases
May cause parental anxiety and will require additional expert counseling and follow-up
Over time, VUSs are being categorized as benign or pathogenic as additional reports are incorporated into databases
The data from a major NICHD study in 2012 provided the support for introducing microarray technology into prenatal clinical care, with previous studies highlighting the benefits in the postnatal period and beyond. Similar to a conventional karyotype, microarrays can detect aneuplodies and larger structural chromosomal changes. In addition, microarray technology allows for the identification of small duplications and microdeletions that would otherwise go unreported. There are limitations and expert counseling is required to provide optimal care and informed decision making.
Fetal structural anomalies on prenatal ultrasound or stillbirth
Microarray replaces conventional karyotype (1A)
Patient undergoing invasive testing and no anomalies identified
Both options, conventional karyotype and microarray, should be discussed (1B)
SOGC & CCMG
Microarray should be offered following a normal rapid aneuploidy screen when
Multiple fetal malformations are detected (II-1A) or
NT ≥3.5 mm (II-2B)
Microarray is a first-line test in the initial postnatal evaluation in the following clinical scenarios
Multiple anomalies not specific to a well-delineated genetic syndrome
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Disclosure of Unlabeled Use
This educational activity may contain discussion of published and/or investigational uses of agents that are not indicated by the FDA. The planners of this activity do not recommend the use of any agent outside of the labeled indications.
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presented in this activity is not meant to serve as a guideline for patient management. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patient’s conditions and possible contraindications and/or dangers in use, review of any applicable manufacturer’s product information, and comparison with recommendations of other authorities.
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