Mitochondrial disorders of the nuclear genome

Abstract

Background: Mitochondrial myopathies are regulated by two genomes: the nuclear DNA, and the mitochondrial DNA. While, so far, most studies have dealt with mitochondrial myopathies due to deletions or point mutations in the mitochondrial DNA, a new field of investigation is that of syndromes due to mutations in the nuclear DNA. These latter disorders have mendelian inheritance.

Results: Three representative cases have been selected: one with COX deficiency and a Leigh syndrome due to a SURF1 gene mutation, one due to a defect of Coenzyme Q synthesis and one with dominant optic atrophy due to a mutation in the OPA1 gene.

Conclusions: Future developments will show that many neurodegenerative disorders are due to mutations of nuclear genes controlling mitochondrial function, fusion and fission.

Figure 1

Case 3: Diffuse optic atrophy on fundus photograph.

Figure 2

Case 3: Brain MRI showing bilateral optic nerve atrophy.

Figure 3

Case 3: Muscle biopsy showing atrophic fibres on Haematoxylin-Eosin stain (A), mini fibre type-grouping on acid ATP-ase (B), and aggregates of abnormally-shaped mitochondria on electron microscopy (C).