Atypical male and female presentations of FLNA-related periventricular nodular heterotopia

Periventricular nodular heterotopia, the most common form of cortical malformation in adulthood, is characterized by nodules of neurons ectopically placed along the lateral ventricles. Classically, ectopic nodules are bilateral and symmetric defining bilateral periventricular nodular heterotopia (BPNH). BPNH can lead to epilepsy and intellectual disability of variable severity. The X-linked dominant form of BPNH, related to mutations in FLNA encoding filamin A, is the major cause of BPNH, causing prenatal and neonatal lethality in males that explain the excess of affected women. However, few living males have been described with this condition. In addition, mutations in FLNA have been also exceptionally associated with unilateral nodular heterotopia. We describe here three new patients, all carrying a novel missense mutation in FLNA. Two of the patients were adult males with BPNH; both had normal cognitive development and one did not manifest any seizure until he died at age 57. The last patient was a female adult with epilepsy and focal nodules essentially located along the right ventricle. We compare the clinical and imaging data of our patients with those of previously described similar cases. The type and location of FLNA mutations leading to such atypical presentations are discussed.