-Related Disorders as Key Differential Diagnosis of Cavitating Leukoencephalopathy.

Genetic leukoencephalopathies represent an expanding group of inherited disorders associated with involvement of brain white matter. Cystic degeneration has been previously described with some acquired or inherited leukoencephalopathies. We describe a 6-month-old Brazilian boy with a 2-month history of severe and rapidly progressive developmental and psychomotor regression and seizures. Neurological examination showed spastic tetraparesis and lethargy. Neuroimaging showed diffuse and symmetric cavitating cystic leukoencephalopathy. Whole-exome sequencing revealed compound heterozygous mutations in the gene, providing definite genetic diagnosis of multiple mitochondrial dysfunction syndrome type 1. We report a rare presentation of early-onset cystic leukoencephalopathy in the context of multiple mitochondrial dysfunction syndrome type 1.