Tissue distribution and transmission of mitochondrial DNA deletions in mitochondrial myopathies

Abstract

By using a combination of Southern blot hybridization analysis, polymerase–chain reaction amplification, and direct nucleotide sequencing, we studied deletions of mitochondrial DNA (mtDNA) in several nonfamilial patients with progressive external ophthalmoplegia and Kearns‐Sayre syndrome, and in some of their direct relatives. Results suggest that the heteroplasmic mtDNA populations are already present at a very early stage of development, and that there is no direct transmission of mtDNA heteroplasmy by maternal inheritance.