Common kidney manifestations of mt electron transport defects in patients include tubulointerstitial injury and isolated tubular dysfunction, for example, Fanconi’s syndrome, or renal tubular acidosis.35–37 Nephrotic syndrome is less common and frequently involves defects in coenzyme Q10 synthesis.36 Primary mt complex III deficiencies, such as mutations in mitochondrially encoded cytochrome b, mt complex III assembly protein BCSL1 (BCS1 homolog, ubiquinol-cytochrome c reductase complex chaperone), or QPC, are rare. Here, MT-CYB is linked to nephrotic syndrome.