Identifying clinically significant chromosomal abnormalities
Chromosomal microarray (CMA) testing generates large amounts of complex data that require a high level of expertise to accurately assess and classify each abnormality detected. Our laboratory directors review thousands of CMA tests each year and are actively involved in the field of genomics, helping to create testing standards and shape practice guidelines. Our staff are American Board of Medical Genetics and Genomics certified laboratory directors. Every CMA test performed at Mayo Clinic is supported by the experience and expertise of our laboratory directors, ensuring we not only provide test results but clinically actionable interpretations.
Benefits of our testing
Manual review of software output to eliminate common errors, such as misidentification, background noise, and failure to detect mosaicism
Examination of every copy number finding regardless of size to determine the importance and relevance of gene content, rather than a strict reliance on reporting size criteria
Integration of historical data on common benign polymorphisms and previously reported abnormalities to improve accuracy of interpretation
Extensive literature and database searches to ensure accurate and up-to-date classification of abnormalities
Performance of parental studies, when necessary, to determine whether the chromosomal abnormality is inherited or de novo, to help determine if it is benign or pathogenic and if future pregnancies are at risk
Determination of maternal cell contamination to assess if fetal (not maternal) DNA is available for analysis from prenatal specimens
When to consider testing
Diagnostic prenatal testing
The American Congress of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine recommend CMA in patients with a pregnancy demonstrating one or more major structural abnormalities on ultrasound when undergoing invasive prenatal diagnosis.
In cases of developmental delay and birth defects
The American College of Medical Genetics recommends CMA as a first-tier, postnatal test for individuals with multiple anomalies that are not specific to well-delineated genetic syndromes, apparently nonsyndromic developmental delay or intellectual disability, or autism spectrum disorders. CMA is also an appropriate follow-up test for individuals with congenital anomalies with a previously normal conventional chromosome study.
In cases of intrauterine fetal demise or stillbirth
ACOG recommends CMA analysis of fetal tissue (e.g., amniotic fluid, placenta, or products of conception) in cases of intrauterine fetal demise or stillbirth. CMA testing increases the success rate of obtaining results and improves detection of causative abnormalities. This testing is also available on both fresh and formalin-fixed, paraffin-embedded tissue, expanding the clinical situations in which this testing can be used.
Webinar — Chromosome Analysis vs. Chromosomal Microarray
In a rapidly advancing field, selecting the appropriate genetic tests can be a challenging task. Chromosome analysis, which was once the preferred genetic test for a wide variety of congenital abnormalities, is now one of the most frequently mis-ordered genetic tests at Mayo Clinic Laboratories.
Learn more about how to order these evaluations at your institution.