TBC1D20 and Micro syndrome: Additionally, the cellular functions of TBC1D24 are involved in regulating the small GTP-binding protein, ARF6 [9,53,54]; (3) truncating mutations in TBC1D23 are responsible for a form of pontocerebellar hypoplasia, by affecting dense core vesicles and lysosomal trafficking dynamics [55]; and (4) mutated TBC1D20 has been identified in 77 families affected by the Warburg micro syndrome, which is characterized by eye, brain, and endocrine abnormalities [56].