One of the major strengths of studying CNVs is that the methods for association testing are similar, by and large, to examining common variants. Simultaneous examination of SNPs and CNVs in large samples may identify whether CNVs play a significant role in depression and what their importance is relative to common variants. One of the major drawbacks of association testing with CNVs is that catalogs of these variants do not exist with the same level of number or specificity as they do for SNPs. For example, the location, size, and boundary of CNVs in these publicly available resources have been relatively imprecise. As a result, opportunities for misclassification of variants is much higher for CNVs than for SNPs.128 Efforts are now underway to provide a more comprehensive catalog of CNVs (see for example: http://www.sanger.ac.uk/research/areas/humangenetics/cnv/). Moreover, until recently there has also not been a commercially-available genotyping array that could detect both SNPs and CNVs. With the advent of the “PsychChip,” a customized genotyping chip for psychiatric phenotypes, investigators will soon be able to simultaneously examine multiple genetic variants, including SNPs, CNVs,
