Oculo-auriculo-vertebral spectrum associated to progressive external ophthalmoplegia. Biological, laboratory, electrophysiological and clinical aspects

The authors discuss about the relationships between oculoauriculo- vertebral spectrum (OAVS), a malformative condition affecting eyes, ears and vertebral structures mainly derived from neural crests, and autosomal dominant progressive external ophthalmoplegia (adPEO) – an electron transport chain disorder characterized by palpebral ptosis and muscular symptoms – on the basis of laboratory data and clinical signs in a case belonging to a family in which symptoms of both diseases occur. Hemifacial microsomia and ears abnormalities were the main neural crest cells (NCC) derived signs for OAVS diagnosis. Palpebral ptosis and the associated hyperlactacidemia with high Lactate to Pyruvate ratio were main signs for the suspicion of adPEO, but the diagnosis was proposed by clinical, biochemical, electrophysiological and genetic methods because the biopsy not always is diagnostic, as in our case. The association of two groups of symptoms (malformed, NCCrelated, and myopatic-electron transport related) in the same subject as observed in our case and partially in the family, may be ascribed to nuclear abnormalities and mitochondrial electron transport disorder, respectively, as well as to a possible common etiopathogenetic mechanism. In some cases of OAVS, the malformations may be consequent to oxidative phosphorilation disease (OXPHOS) derangement, as previously demonstrated; the extensive determination of lactacidemia may be important to address the research on OAVS patients in the mitochondrial/OXPHOS genetic domain, with advantage in the knowledge of OAVS pathogenesis.