06/30/2026
Understanding Genetic Testing
A Patient & Family Guide for our families!
Why Has Genetic Testing Been Recommended?
Genes are the body's instruction manual. They tell our bodies how to grow, develop, and function. Sometimes a child is born with a change in these instructions that can explain developmental delay, autism, epilepsy, birth defects, or other neurological disorders. Genetic testing helps us look for these changes.
Think of Your DNA as a Giant Instruction Book
Imagine your DNA is a book containing over 3 billion letters and approximately 20,000 chapters (genes). Different genetic tests examine this instruction book in different ways.
1. Chromosomal Microarray (CMA) – Looking for Missing or Extra Pages
Checks whether large sections of DNA are missing or duplicated.
Think of it as looking through the instruction book to see if entire pages or chapters are missing, copied twice, or out of place.
Best for: Developmental delay, autism spectrum disorder, intellectual disability, birth defects, and multiple congenital anomalies.
Can detect: Missing pieces (deletions) and extra pieces (duplications).
Cannot detect: Small spelling mistakes within individual genes.
2. Whole Exome Sequencing – Reading the Important Chapters
Reads the protein-coding genes (the exome) looking for disease-causing spelling mistakes.
Best for: Rare genetic disorders, epilepsy, developmental delay, intellectual disability, neurological disorders, and unexplained conditions.
May miss some changes outside genes or certain structural changes.
3. Whole Genome Sequencing – Reading the Entire Instruction Book
Reads all of the DNA, including genes and the areas between them.
Can identify the broadest range of genetic changes, including some that other tests may miss.
Comparing the Tests
• Microarray: Looks for missing or duplicated pages.
• Exome: Reads the important chapters.
• Genome: Reads the entire instruction book.
Understanding Your Results
Positive Result
A genetic change has been identified.
This finding may explain your or your child's medical condition. Sometimes, however, the finding is incidental, meaning it is unrelated to the reason testing was performed.
Your physician will review the results with you and explain whether the finding is responsible for the medical condition. Genetic counseling will be offered to help you understand the result, discuss implications for other family members, and answer any questions.
Negative: No disease-causing change is found, but this does not completely rule out a genetic condition.
Variant of Uncertain Significance (VUS): A change is found, but we do not yet know whether it causes disease. As science advances, these variants may be reclassified.
Questions?
If you have questions about genetic testing or your results, please discuss them with your healthcare provider. We are here to help you understand what the results may mean for your child and your family.
Center of Excellence in Pediatric Neurology (CEPN)
Ashutosh Raina, MD
Michelle Nguyen, NP
Mellissa Jacobs, NP
Committed to compassionate, evidence-based neurological care for children and their families.
