Individuals from 33 unrelated Australian families with optic atrophy were screened for 10 different single base alterations in mitochondrial DNA (mtDNA) associated with Leber hereditary optic neuropathy (LHON) using direct polymerase chain reaction amplification of blood spots collected on Guthrie cards. This method using blood spots allows easily accessible screening forLHON mtDNA mutations wi...

T years ago, based on the knowledge of cytosine methylation in higher organisms and the newly discovered bacterial adenine methyltransferase, Riggs (1) and Holliday and Pugh (2) independently proposed that the covalent modification of DNA by methylation might serve as a means to propagate heritable expression states in eukaryotes. In the years since, the association between cytosine methylation...