ANKRD11 and Intellectual disability: According to previous studies analyzing genotype–phenotype correlations in KBG syndrome, lower ANKRD11 gene expression is associated with abnormal neuronal differentiation; hence, overall developmental delay and the frequency of intellectual disability/learning difficulty were higher in patients with deletion mutations than in those with missense variants (Gao et al., 2022; Li et al., 2021; Willemsen et al., 2010).