AN AUTOSOMAL LOCUS PREDISPOSING TO DELETIONS OF MITOCHONDRIAL-DNA

The molecular mechanisms by which the nuclear genome regulates the bio synthesis of mitochondrial DNA (mtDNA) are only beginning to be unrave lled. A naturally occurring in vivo model for a defect in this cross-t alk of two physically separate genomes is a human disease, an autosoma l dominant progressive external ophthalmoplegia, in which multiple del etions of mtDNA accumulate in the patients' tissues. The assignment of this disease locus to 10q 23.3-24.3 is the first direct evidence for involvement of both nuclear and mitochondrial genomes in a single diso rder.