PIK3CD and autism spectrum disorder: Recent studies suggest that the PIK3CD/p110δ catalytic subunit is one such isoform relevant for neurological development and disease, with PIK3CD being associated with increased risk for schizophrenia (Law et al., 2012), and increased expression being identified in patients with schizophrenia or autism spectrum disorder (Law et al., 2012; Poopal et al., 2016; Hood et al., 2019).