One of the first genome-wide technologies implemented in epilepsy was CMA to detect deletions and duplications, also known as copy number variants (CNVs), and numerous studies have consistently shown that de novo copy number changes are causative in 5% to 10% of DEE.5–7 Across broad neurodevelopmental disorders including intellectual disability (ID) and autism with or without epilepsy, the diagnostic yield of CMA is even higher.8 Chromosomal microarray moved into the clinical setting shortly after successes in the research lab and has been recommended as a first-line test in the workup of neurodevelopmental disorders,8 including epilepsy.