Gnb5-Related Intellectual Disability-Cardiac Arrhythmia Syndrome

A rare genetic disease characterized by intellectual disability, developmental delay, language deficits, and cardiac arrhythmia (most commonly sick sinus syndrome). Additional reported features include epilepsy, hypotonia, retinal abnormalities, nystagmus, attention deficit hyperactivity disorder, autism, and gastroesophageal reflux. The severity of the phenotype is highly variable.