TBC1D23 and pontocerebellar hypoplasia: Emphasizing the importance of TBC1D23 in human development, homozygous mutations of the TBC1D23 gene has recently been found in patients diagnosed with pontocerebellar hypoplasia (PCH) (Ivanova et al., 2017; Marin-Valencia et al., 2017; Harripaul et al., 2018).