Neurodevelopmental disorder with nonspecific brain abnormalities is a highly variable syndrome characterized by impaired intellectual development and behavioral abnormalities associated with structural changes on brain imaging. Some patients have seizures, hypotonia, and scoliosis/kyphosis. Cognitive function ranges from severely impaired to the ability to attend schools with special assistance (summary by Fischer-Zirnsak et al., 2019).

Developmental delay, hypotonia, and impaired language (DEDHIL) is a neurodevelopmental disorder characterized by variably impaired intellectual development usually with hypotonia, mild motor delay, and language difficulties. Affected individuals may also have nonspecific dysmorphic facial features, gastrointestinal problems, and abnormalities on brain imaging (Stephenson et al., 2022).