Sporadic leber hereditary optic neuropathy in Australia and new Zealand

Background: Leber hereditary optic neuropathy (LHON) is one of the more common forms of hereditary optic neuropathy and one of the few mitochondrial neuropathies. Prior to the advent of molecular DNA testing, the diagnosis depended on the recognition of typical fundal changes, as well as a family history of maternal transmission. Sporadic cases were therefore diagnosed with a level of uncertainty. The aim of this study is to identify the proportion of patients with idiopathic bilateral optic neuropathy/atrophy who are suffering from LHON. Methods: Requests were sent to all ophthalmologists and neurologist in Australia and New Zealand for blood or hair follicle samples of patients with diagnosis of bilateral optic neuropathy/atrophy of uncertain aetiology for DNA testing by restriction endonuclease analysis. Results: One hundred and fourty-four samples were received, of which 96 were sporadic cases of idiopathic optic atrophy. Eleven of these sporadic patients were found to harbour pathogenetic mitochondrial point mutations associated with LHON. Conclusions: Our results indicated that 11% of patients with bilateral optic neuropathy/atrophy of uncertain aetiology are suffering from LHON. Comparing this data with all the known familial cases of LHON, we report that at least 8% of all LHON cases in Australia are sporadic. We concluded that mtDNA testing for LHON in patients with idiopathic optic atrophy should be included in the initial laboratory work-up.