Genetic testing revealed that the six symptomatic (insulinomatosis or mild diabetes; classification here after laboratory analyses) individuals studied from generations III-V (Figure 1, III1; IV3, 4; V2, 3, 5) all carried the MAFA variant, but only three of them had the PROX1 variant (IV3, 4; V5). Here, PROX1 is linked to diabetes mellitus.