GRN and hyperinsulinemic hypoglycemia, familial, 4: It may well be that this periventricular distribution represents a particular pathogenetic feature of GRN mutations: progranulin deficiency has been shown to be associated with blood-brain barrier dysfunction and increased permeability (Jackman et al., 2013), which have been shown to be associated with periventricular lesions (Haller et al., 2013).