CUL4B and X-linked intellectual disability, Cabezas type: CUL4B is a haploinsufficient gene (HI score = 3), and frameshift mutations in its coding region can lead to a loss of function, thereby causing Cabezas syndrome (Thus, PVS1 applied) (Zheng et al., 2002; Della Vecchia et al., 2023; Magalhaes et al., 2023; Nakamura et al., 2019) (Figure 1).