Update on a previously reported missense mutation: The c.1160 C>A mutation in the UGT1A1 gene result in Crigler-Najjar syndrome type 1 The absence of the UGT1A1 enzyme activity due to a defect in the I UGT1A1 i gene (UGT1A1; MIM# 191740) result in CN-I (Gailite et al., 2020). Patients with CN-II have residual UGT1A1 enzyme activity.