Homozygous or compound heterozygous variants in the GNB5 gene have been associated with either IDDCA (Intellectual Developmental Delay with Cardiac Arrhythmia, MIM#617173) or LADCI (Language delay and ADHD/Cognitive Impairment with or without cardiac arrhythmia, MIM#617182) human syndromes [66,120,121,122,123,124,125]. This evidence concerns the gene GNB5 and cardiac rhythm disease.