PDE4B and schizophrenia: Indeed, GWASs have associated PDE4B SNPs with PTSD (Gelernter et al., 2019; Meier et al., 2019; Nievergelt et al., 2024), as well as schizophrenia (Trubetskoy et al., 2022) and substance use disorders (Hatoum et al., 2023) that are often comorbid with it (Kessler et al., 1995).