CNKSR2 and Global developmental delay: Since the initial characterization of a boy affected with a pathogenic variant in CNKSR2 by Houge et al. [7] (mental retardation, X-linked, Houge type (MRXSHG), MIM 301008), there have been a total of 20 affected males described in the literature, all with a consistent clinical phenotype of intellectual disability, developmental delay, and epilepsy [1, 2, 5, 6, 15, 17, 20].