Any autosomal dominant intellectual disability in which the cause of the disease is a heterozygous mutation in the GNB1 gene. It is characterized by global developmental delay, intellectual disability, hypotonia, structural brain abnormalities, and seizures. Other less common findings include dystonia, visual impairment, behavior problems, growth delay, craniofacial defects, and genitourinary abnormalities in males. The disease is intellectual disability, autosomal dominant 42 (Monarch Disease Ontology id MONDO_0014855). Also known as: GNB1-related disorder, GNB1-related neurodevelopmental disorder, MRD42, autosomal dominant intellectual disability 42, autosomal dominant mental retardation 42, global developmental delay-neuro-ophthalmological abnormalities-seizures-intellectual disability syndrome, intellectual developmental disorder, autosomal dominant 42, intellectual disability, autosomal dominant type 42.