This paper provides a brief summary and commentary on the growing literature and current developments related to the genetic underpinnings of posttraumatic stress disorder (PTSD). We first briefly provide an overview of the behavioral genetic literature on PTSD, followed by a short synopsis of the substantial candidate gene literature with a focus on genes that have been meta-analyzed. We then discuss the genome-wide association studies (GWAS) that have been conducted, followed by an introduction to other molecular platforms used in PTSD genomic studies, such as epigenetic and expression approaches. We close with a discussion of developments in the field that include the creation of the PTSD workgroup of the Psychiatric Genomics Consortium, statistical advances that can be applied to GWAS data to answer questions of heritability and genetic overlap across phenotypes, and bioinformatics techniques such as gene pathway analyses which will further advance our understanding of the etiology of PTSD.