A different proposed nosology classifies the severe phenotype of GNB5-related neurodevelopmental disorder as an intellectual developmental disorder with cardiac arrhythmia (IDDCA, OMIM 617173, ORPHA: 542306), which is consistent with LDMLS1; meanwhile, the milder disorder, which manifests as language delay, attention deficit/hyperactivity disorder, and cognitive impairment with or without cardiac arrhythmia (LADCI; OMIM: 617182), is consistent with LDMLS2 [29,30,31,32]. Here, GNB5 is linked to cardiac arrhythmia.