PDX1 and maturity-onset diabetes of the young type 4: It is noted here, however, that dominant monogenic MODY4 mutations in the PDX-1 gene in humans are not necessarily equivalent to PDX-1 heterozygosity in mice or humans, because it has been reported that recessive mutations in the PDX-1 gene also lead to susceptibility to Type 2 diabetes in humans [49,50,51,52].