DLD and pyruvate dehydrogenase E3 deficiency: Dihydrolipoamide dehydrogenase (DLD) deficiency (MIM #246900) is a rare autosomal recessive mitochondrial disorder caused by pathogenic variants in the <i>DLD</i> gene, which encodes the E3 subunit common to multiple mitochondrial enzyme complexes, including pyruvate dehydrogenase (PDHc) and α-ketoglutarate dehydrogenase (αKGDHc).