Mitochondrial Myopathy And Sideroblastic Anemia

Mitochondrial myopathy and sideroblastic anemia belongs to the heterogeneous family of metabolic myopathies. It is characterised by progressive exercise intolerance manifesting in childhood, onset of sideroblastic anaemia around adolescence, lactic acidaemia, and mitochondrial myopathy.

Epidemiology

Less than 10 cases have been described so far.

Etiology

A 656C-->T mutation in the nuclear pseudouridine synthase 1 gene (PUS1), localised to 12q24.33, has recently been identified in some patients. Deficient pseudouridylation of mitochondrial tRNAs may be responsible for the oxidative phosphorylation disorder.

Diagnostic methods

Muscle biopsy demonstrates low activity of complexes 1 and 4 of the respiratory chain and paracrystalline inclusions can be revealed in most mitochondria by electron microscopy.

Genetic counseling

Transmission is autosomal recessive.