UQCRQ encodes ubiquinol-cytochrome c reductase complex III subunit VII, a crucial component of the mitochondrial electron transport chain that facilitates oxidative phosphorylation 1. The protein participates in complex III (cytochrome b-c1 complex), which catalyzes electron transfer from ubiquinol to cytochrome c while translocating protons across the mitochondrial inner membrane during the Q cycle process. Loss-of-function mutations in UQCRQ cause mitochondrial complex III deficiency, characterized by severe psychomotor retardation, extrapyramidal signs including dystonia and ataxia, global dementia, and brain MRI abnormalities showing increased putamen density with decreased caudate and lentiform nuclei size 1. A homozygous missense mutation (p.Ser45Phe) has been identified in patients with this autosomal-recessive disorder, resulting in reduced complex III activity in muscle biopsies. Beyond its primary role in energy metabolism, UQCRQ has emerged as a potential biomarker in various pathological conditions. It shows altered expression in nonalcoholic fatty liver disease 2, kidney transplant rejection 3, and sepsis progression from acute pancreatitis 4. The gene's involvement in oxidative phosphorylation pathways makes it relevant for understanding metabolic dysfunction in diverse clinical contexts, from inherited mitochondrial diseases to complex inflammatory conditions.