The diagnosis of MODY3 (HNF1A) was established in two index cases, one with a well-known frameshift insertion c.872dupC (p. G292Argfs*25) in exon 4 and one with a novel heterozygous missense variant c.8C > A (p.S3Y) in exon 1 of the HNF1A (Table 2). Here, HNF1A is linked to maturity-onset diabetes of the young type 3.