Megalencephalic Leukoencephalopathy with Subcortical Cysts-a New Child Leukoencephalopathy

Yuan Bao-Qiang; Marjo S.van der Knaap

Abstract：Here we review a new variety of leukoencephalopathy with infantile megalencephaly and discrepant clinical course (MLC, MIM: 604004). These children bad megalencephaly in the first year of life, with or without mild delay of motor function and/or seizures. After a few years, motor handicap was slowly progressive with unsteady gait,serious cerebellar ataxia and mild plasticity. Eventually most of patients were confined to a wheelchair. Meanwhile mental development was relatively preserved, although the learning problems was increased from the midway of elementary school. Most of patients had tonic-clonic seizure and some might advance to status epilepticus. Antiepileptic drugs may effectively control seizure. The disorders of known metabolic defects were excluded. Neurophysiological examination showed that EEG had interictal epileptic discharges on the generalized slow wave background in most patients. The cerebral white matter had diffuse abnormality, with swelling of white matter, and cysts in the frontoparietal and anterior-temporal lobes on MRI examnation. Some central white matter structures were spared, such as corpus callosum. The severity of lesions on MRI is inconsistent with the clinical signs. Pathogenesis of this disease was unknown. The pathological findings found a spongiform leukoencephalopathy due to myelin splitting and intramyelinic vacuole formation but without myelin loss. This disease had probably an autosomal recessive inheritance. The gene KIAA027 on 22qtel was responsible for MLC.