Mitochondrial cytopathies include a heterogeneous group of diseases that are characterized by impaired oxidative phosphorylation. Current evidence suggests that renal involvement is probably more frequent than originally suspected but remains subclinical in a significant number of patients or is underestimated due to the severity of other clinical manifestations. Until recently, these diseases were thought to develop primarily in pediatric patients but patients that become symptomatic only in adulthood are now well recognized. From a renal standpoint, many patients with severe systemic disease and several patients with oligo-symptomatic clinical pictures have tubular defects, ranging from isolated tubular wasting of electrolytes to complete forms of renal Fanconi syndrome.
Fanconi syndrome is associated with renal proximal tubular dysfunction. The main pathogenic feature is a generalized reabsorption defect, leading to the wasting of phosphate, amino acids, glucose, and bicarbonate in erratic degrees. Documentation of urinary and serum albumin, urate, glucose, phosphate, amino acids and bicarbonate can help make a diagnosis of a tubulopathy.
Aside from rare cases of tubulo-interstitial and cystic diseases, other patients present with glomerular diseases that correspond in the majority of cases to focal segmental glomerulosclerosis lesions. Two specific entities should be singled out, namely the 3243 A>G mutation in the gene encoding for the mitochondrial leucine tRNA because it represents the most frequent form of mitochondrial glomerulopathy, and defects in the biosynthesis of coenzyme Q10 because they represent one of the few treatable forms of mitochondrial cytopathies.
Coenzyme Q10 biosynthesis defects are rare but are important to be recognized as they represent a unique group of mitochondrial diseases that may respond to medical treatment. Glomerular involvement may be isolated, in particular at presentation, or may occur in the context of a multisystemic disorder.
Mitochondria Damage and Kidney Disease
Wellcome Centre for Mitochondrial Research website:
Lily Foundation website, the leading mitochondrial disease charity in the UK: