INS and Dravet syndrome: Part of the insulin binding site of INSR and the α–β cleavage site are located within the FnIII domain.[6] Hosoe et al showed that all missense mutations expected to severely impair hydrophobic core formation and FnIII structural domain stability cause DS, while all mutations expected to produce local instability and not affect FnIII structural domain folding cause RMS.[7] Patients with severe INSR mutation-induced insulin resistance syndrome (DS or RMS) usually have a pure or compound heterozygous mutations in INSR.