A neurologist’s guide to genome-wide association studies

Genome-wide association studies are utilized for gene discovery in common diseases. Genotypes of large groups of unrelated patients are compared to controls. This has become feasible due to the recent technical advances in genomics and convincing positive results are now regularly being published. This review is an accessible introduction to the genetic and technical knowledge needed to interpret such studies. Genome-wide association studies are being applied to many neurologic diseases. Here we use idiopathic generalized epilepsy as an example to highlight the phenotyping, sample size, and statistical issues that must be addressed in such studies. These studies are likely to transform our understanding of complex neurologic diseases in the next few years. CAE = childhood absence epilepsy; CDCV = common disease-common variant; CDMRV = common disease-multiple rare variant; CNV = copy number variation; GTCS = generalized tonic-clonic seizures; GWAS = genome-wide association studies; IGE = idiopathic generalized epilepsy; JAE = juvenile absence epilepsy; JME = juvenile myoclonic epilepsy; LD = linkage disequilibrium; MS = multiple sclerosis; RLS = restless legs syndrome; RR = relative risk; SNP = single nucleotide polymorphism.