Congenital disorder of deglycosylation-2 (CDDG2) is an autosomal recessive disorder with variable associated features such as dysmorphic facies, impaired intellectual development, and brain anomalies, including polymicrogyria, interhemispheric cysts, hypothalamic hamartoma, callosal anomalies, and hypoplasia of brainstem and cerebellar vermis (Maia et al., 2022). For a discussion of genetic heterogeneity of congenital disorder of deglycosylation, see CDGG1 (615273).

Neurodevelopmental disorder with language impairment, autism, and attention deficit-hyperactivity disorder (NEDLAAD) is characterized by speech delay and language difficulties, behavioral abnormalities, and variably impaired intellectual development (in most patients). Additional features seen in some patients include motor delay, mild distal skeletal anomalies, mild ocular anomalies, and mild nonspecific dysmorphic features (Pavinato et al., 2023).