In this issue of�Critical Care Clinics,�guest�editors�Drs.�Robert M.�Kliegman�and Brett J.�Bordini�bring�their�considerable expertise to the topic of�Undiagnosed and Rare Diseases in Critical Care. Top experts in the field cover key topics such�as critical genetic arrhythmia disorders,�uncommon causes of rhabdomyolysis,��status epilepsy syndromes,�autoimmune encephalitis, rapid-onset paralysis and weakness,�and more.