Remind me again what disease we are studying? A population genetics, genetic analysis, and real data perspective on why progress on identifying genetic influences on common epilepsies has been so slow.

In this chapter, we will use the concepts and perspective of population genetics and genetic analysis to discuss the trends that are currently popular in the epilepsy genetics literature. We will also show that some of the recent approaches to understanding epilepsy genetics are unlikely to lead to insight into the causes of the most common epilepsies. Much effort has been directed toward very rare influences on epilepsy expression and away from approaches that could shed light on the most heritable epilepsies. The latest genetic technology, e.g., exome sequencing and copy number variants (CNV) analysis, has been applied without proper consideration of the important principles of population genetics, inheritance, or phenotype definition that are critical in common disease studies. We will show that ignoring these issues has led to unlikely suppositions about etiology and about which genes should be pursued. We also suggest that, taken together, the existing evidence supports a neurodevelopmental origin for common epilepsies. We recommend a return to thorough phenotype definition and family studies and a more careful and thoughtful application of the new technology.