Chromosomal microarray technology (CMA) facilitates the genetic diagnosis of intellectual disabilities, autism spectrum disorder, and congenital abnormalities in children. Previously, G-band karyotyping was the test performed for this purpose but it could only identify very large chromosomal abnormalities and was not very sensitive. Being a molecular rather than microscopic technique, CMA is far more sensitive for identifying genetic abnormalities and is now the test of choice. We interview David H. Ledbetter, MD, and Christa Lese Martin, PhD, from Geisinger Health System, authors of this JAMA Insights article. Articles discussed in this episode: Chromosomal Microarray Testing for Children With Unexplained Neurodevelopmental Disorders New Approaches to Molecular Diagnosis