Branched chain amino acid levels are known to be low in presence of BCKDH derepression following BKDK inactivation [17] and also in other conditions (e.g., nutritional deficiency), but none of these conditions can readily be reconciled with the proposed mechanisms of LIPT1 deficiency (Figure 4), as well as with some of our in vitro studies (Figure 1C), or the overall amino acid profile shown by our patient at diagnosis and throughout follow-up (Table 1). Here, LIPT1 is linked to nutritional deficiency disease.