EPIDEMIOLOGY OF LEBERS HEREDITARY OPTIC NEUROPATHY IN AUSTRALIA

Leber's hereditary optic neuropathy (LHON) is the most common form of hereditary optic neuropathy in Australia, accounting for 2% of all cas es of legal blindness in people under the age of 65 years. All multige nerational pedigrees have one of the three definite primary mitochondr ial DNA mutations at nucleotides 3460, 11778, or 14484. Secondary LHON mutations are also present, but are always associated with one of the primary mutations. Ar present, there are 150 visually affected patien ts from more than 2,000 LHON carriers in Australia (population, 17 mil lion). Of the affected individuals located by genealogical searching n early one third-particularly women, children, and those having no clos e family member who was affected-did not know their correct diagnosis. This finding shows that LHON is frequently missed. The risk of loss o f vision for members of homoplasmic LHON families in Australia (20% fo r males and 4% for females) is lower than that previously reported in Europe. Moreover, the risk of loss of vision has fallen over the last 150 years, the most likely explanation being that one or more environm ental factors has changed. (C) 1994 Wiley-Liss, Inc.