Mitochondrial Disorders in Adults.

Mitochondrial Disorders (MD) include a heterogeneous group of inherited disorders due to molecular defects mainly affecting the mitochondrial oxidative phosphorylation system. Because the respiratory chain is under control of two different genomes (nuclear DNA-nDNA and mitochondrial DNA-mtDNA), mitochondrial genetics is quite complex and may justify the extreme clinical heterogeneity of these diseases. Clinically, MD usually involve multiple tissues, mainly affecting organs with high energy request as central nervous system and skeletal muscle. They may present at any age, with different onsets, clinical presentation and progression from an isolated involvement of vision or hearing to a multisystemic degenerative disorders with stroke-like episodes, peripheral neuropathy, ophthalmoparesis, seizures, cardiopathy, hepatopathy, endocrinopathies, etc. Over the last 50 years, it became evident that MD represent an important part of the general medicine. The complexity of clinical and genetic spectrum of those disorders is still increasing. The aim of this review is to walk through mitochondrial genetics, highlighting novel clinical entities.