Approximately 20 families have been reported so far with heterozygous loss-of-function mutations in NEUROD1. The first pathogenic variant E110K was reported in an Icelandic MODY6 family, and following the missense variants, S159P, H241Q, and R103P in NEUROD1 were identified worldwide [122]. Here, NEUROD1 is linked to maturity-onset diabetes of the young type 6.