Mutations in TTC19 were described for the first time in three Italian individuals from two unrelated families with young-onset characterized by slowly progressive encephalopathy and isolated cIII deficiency, and in a fourth Italian individual with an adult-onset characterized by subacute, rapidly progressive neurological failure and isolated cIII deficiency (Ghezzi et al., 2011). This evidence concerns the gene TTC19 and hyperinsulinemic hypoglycemia, familial, 4.