Symptoms are also used to guide the differential diagnosis of the two syndromes; for example: in NMS, patients may have stiffness, rhabdomyolysis (characterized by muscle fiber destruction), and increased serum creatine phosphokinase (CPK) levels, which should not occur in SS [90]. However, some SS case reports show that patients present rigidity, sometimes associated with hyperreflexia [91-94] and increased serum CPK levels [92,95,96]. The gene discussed is PIK3C2A; the disease is neuroleptic malignant syndrome.