02625nas a2200541   4500000000100000000000100001008004100002260001200043653001400055653001500069653001800084653001000102653003000112653001900142653003000161653002100191653001700212653001500229653001100244653002300255653005800278653003000336653003100366653003100397653001900428653003100447653001600478653001700494100002500511700002500536700002100561700002200582700001900604700001800623700002100641700002400662700002200686700001700708700004800725700004300773700002400816700002400840245007700864300001200941490000800953520110800961022001402069       2020                            d  c2020-0510aArtifacts10aAutomation10aConsanguinity10aExons10aGain of Function Mutation10aGene Frequency10aGene Knockdown Techniques10aGenes, Essential10aHeterozygote10aHomozygote10aHumans10aHuntingtin Protein10aLeucine-Rich Repeat Serine-Threonine Protein Kinase-210aLoss of Function Mutation10aMolecular Targeted Therapy10aNeurodegenerative Diseases10aPrion Proteins10aReproducibility of Results10aSample Size10atau Proteins1 aEric Vallabh Minikel1 aKonrad J. Karczewski1 aHilary C. Martin1 aBeryl B. Cummings1 aNicola Whiffin1 aDaniel Rhodes1 aJessica Alföldi1 aRichard C. Trembath1 aDavid A. van Heel1 aMark J. Daly1 aGenome Aggregation Database Production Team1 aGenome Aggregation Database Consortium1 aStuart L. Schreiber1 aDaniel G. MacArthur00aEvaluating drug targets through human loss-of-function genetic variation  a459-4640 v5813 aNaturally occurring human genetic variants that are predicted to inactivate protein-coding genes provide an in vivo model of human gene inactivation that complements knockout studies in cells and model organisms. Here we report three key findings regarding the assessment of candidate drug targets using human loss-of-function variants. First, even essential genes, in which loss-of-function variants are not tolerated, can be highly successful as targets of inhibitory drugs. Second, in most genes, loss-of-function variants are sufficiently rare that genotype-based ascertainment of homozygous or compound heterozygous 'knockout' humans will await sample sizes that are approximately 1,000 times those presently available, unless recruitment focuses on consanguineous individuals. Third, automated variant annotation and filtering are powerful, but manual curation remains crucial for removing artefacts, and is a prerequisite for recall-by-genotype efforts. Our results provide a roadmap for human knockout studies and should guide the interpretation of loss-of-function variants in drug development.  a1476-4687