In both CNS type 2 and GS, patients typically present with asymptomatic jaundice and isolated indirect hyperbilirubinemia, although average unconjugated bilirubin levels are often higher in CNS Type 2 (6–20 mg/dL) than in GS (1–5 mg/dL).2,4 Genetic testing of UGT1A1 gene for mutations is diagnostic, although rarely reported. The gene discussed is UGT1A1; the disease is Hyperbilirubinemia.