Some inborn errors of metabolism have been described in association with MCE, like pyruvate dehydrogenase deficiency.21 Another associated condition is homozygous methylenetetrahydrofolate reductase mutation, which causes the accumulation of homocysteine, an amino acid with a neurotoxic sulfur group, leading to neuronal loss.6 Screening for these conditions in suspected cases is essential for diagnosis, and prompt treatment can improve neurological symptoms. This evidence concerns the gene MTHFR and pyruvate dehydrogenase deficiency.