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1 QF-PCR and FISH analysis are two rapid diagnostic methods.
CMA can be used to analyze the entire genetic makeup of an individual and thereby detect genetic changes that may a ect anatomy, development or function. ese genetic changes, often referred to as copy number variants (CNV), can be very large, such as when an extra copy of a whole chromosome is acquired. CNV can also refer to the loss or gain of a much smaller piece of a chromosome.
A method called karyotyping has traditionally been used to identify genetic changes prenatally. Karyotyping entails examining an individual’s chromosomes from cultured cells using a light microscope. Karyotyping provides high diagnostic reliability for detecting large CNV, including extra chromosomes and major structural changes. However, CMA can detect genetic changes that are more than 100 times smaller than those detectable with karyotyping.
CMA is primarily used for prenatal diagnostics in response to fetal anomalies detected by ultrasound, such as structural aberrations in one or more organ, abnormal growth of the fetus or placenta, or unusual amniotic uid volume.
This report evaluates the reliability of the results obtained from CMA for use in prenatal diagnostics. It also evaluates how often additional genetic changes are detected through CMA as compared to karyotyping, QF-PCR or FISH analysis. The report also highlights ethical aspects of using CMA for prenatal diagnosis, and how expectant parents perceive the value of the analysis. Health economic aspects are not addressed in this report.
This evaluation is performed following SBU’s method.
Prenatal diagnosis raises ethical questions about human dignity, parental autonomy, and the health of both the fetus and the parents. is SBU report presents ethically relevant advantages and challenges associated with CMA compared to karyotyping. General ethical aspects of prenatal diagnosis can be found in a 2011 report from the Swedish National Council on Medical Ethics.
The main advantage of using CMA for prenatal diagnosis is that CMA can identify smaller genetic changes than karyotyping. An important ethical problem is the increased di culty of fully informing those involved about all of the potential ndings in a manner that is both clear and understandable. Secondary findings, and variants of uncertain signi cance in particular, can cause concern and may be difficult for parents to use in their decision making process.
Because CMA can detect more genetic changes than karyotyping, it may lead to more problems from an autonomy standpoint, i.e. the individual’s right to self-determination. The increased use of CMA may contribute to the perception that it is the parents’ responsibility to ensure that their o spring do not have any genetically caused health problems. This perception could make it more difficult for parents to feel they can decline the offer of prenatal diagnosis. Increased access to CMA may also allow healthcare professionals to expand their perception of what entails a serious a condition. This could contribute to stigmatization of individuals with the genetic changes that the method is capable of identifying.
How to cite this report: SBU. Prenatal Diagnosis through Chromosomal Microarray Analysis (CMA). Stockholm: Swedish Agency for Health Technology Assessment and Assessment of Social Services (SBU); 2016. SBU report no 246 (in Swedish).
presents a comprehensive, systematic assessment of available scientific evidence. The certainty of the evidence for each finding is systematically reviewed and graded. Full assessments include economic, social, and ethical impact analyses.
SBU assessments are performed by a team of leading professional practitioners and academics, patient/user representatives and SBU staff. Prior to approval and publication, assessments are reviewed by independent experts, SBU’s Scientific Advisory Committees and Board of Directors.