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 cases of legal blindness in people under the age of 65 years. All multigenerational pedigrees have one of the three definite primary mitochondrial 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 patients from more than 2,000 LHON carriers in Australia (population, 17 million). Of the affected individuals located by genealogical searching nearly one third-particularly women, children, and those having no close family member who was affected-did not know their correct diagnosis. This finding shows that LHON is frequently missed. The risk of loss of vision for members of homoplasmic LHON families in Australia (20% for 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 environmental factors has changed. (C) 1994 Wiley-Liss, Inc.