Hyperinsulinism-hyperammonemia syndrome (HI/HA; OMIM 606762) was first described in 1996 by Zammarchi et al. and since then has been shown to be the result of a gain of function mutation in the glutamate dehydrogenase 1 (GLUD1) gene [1, 2]. This evidence concerns the gene GLUD1 and hyperinsulinism-hyperammonemia syndrome.