Cohen syndrome (Online Mendelian Inheritance in Man (OMIM) entry number 216550) is caused by an autosomal recessive (AR) mutation of the vacuolar protein sorting 13 homolog B (VPS13B, also referred to as COH1) gene on chromosome 8q22.2. VPS13B is a transmembrane protein that is thought to function in vesicle-mediated transport and sorting of proteins within the cell and plays a role in the development and the function of the eye, hematological system, and central nervous system. Here, VPS13B is linked to Cohen syndrome.