In 33 (13%) patients, class 4–5 variants were identified in one of four genes usually considered as rarely involved in monogenic diabetes in adults, namely HNF1B (15 cases, 6.0%, among which 10 HNF1B whole-gene deletion), ABCC8 (8 cases, 3.2%), KCNJ11 (3 cases, 1.2%), and INS (7 cases, 2.8%) (Fig. 1, Additional file 2: Tables S3 and S4). Here, HNF1B is linked to diabetes mellitus.