>They explain that given what we now know about polygenicity, the highest-effect-size genes require samples of about 34,000 people to detect, and so any study w

>They explain that given what we now know about polygenicity, the highest-effect-size genes require samples of about 34,000 people to detect, and so any study with fewer than 34,000 people that says anything about specific genes is almost definitely a false positive; they go on to show that the median sample size for previous studies in this area was 345. This is a misleading paraphrasing of what the study said. There are plenty of effects which can be easily demonstrated with smaller sample sizes; it's just not complex effects like depression. What the authors said: >genome-wide association studies (GWASs), which agnostically examine associations at millions of common single-nucleotide polymorphisms (SNPs) across the genome in large samples, have consistently found that individual SNPs exert small effects on genetically complex traits such as depression (18–20). For example, in the most recent GWAS of depression, which utilized a sample of 135,458 case subjects and 344,901 control subjects, the strongest individual signal detected (rs12552; odds ra- tio=1.044, p=6.07310219) would require a sample of ap- proximately 34,100 individuals to be detected with 80% power at an alpha level of 0.05, assuming a balanced case- control design (18).