The rare case of baby girl, early onset, psychomotor development is severely backward, persistent hyperlactic acid and hyperpyruvemia, metabolic acidosis, the head MRI shows septum pellucidum is small, interventricular septum is absent; fornix is unclear, splenium of corpus callosum is small and extruded forward like a canopy.The top of the third ventricle is elevated to the dorsal side, the left paracele enlarge to the right, the left interventricular foramen is obviously enlarged.Intermittent periods EEG a large number of medium and high amplitude spike slow waves, slow waves, and a small amount of multiple spike slow waves are scattered or continuously distributed in the left posterior head (O1, T5). A large amount of low amplitude slow wave can be seen in the bilateral hemisphere.The second-generation gene sequencing found a heterozygous missense mutation of C>T (p.A169v) in the position of chrx-19371287 in the PDHA1 gene of the child, but not in the parent PDHA1 gene.And the diagnosis of pyruvate dehydrogenase E1 α deficiency was identifie.