Diabetes mellitus is the most frequent endocrinopathy associated with
mitochondrial disorders, particularly in patients with duplications of
mitochondrial DNA (
mtDNA). Although
hypoparathyroidism has also been described in
mitochondrial diseases, there have been few molecular studies in these cases, most of which identified the presence of single
mtDNA deletions in the patients' tissues. We studied muscle
DNA of a 12-yr-old patient with incomplete
Kearns-Sayre syndrome and
hypoparathyroidism. Southern analysis showed that muscle
DNA contained three populations of
mtDNA: wild type (26%), deleted (65%), and duplicated (9%). To determine the sequence of the breakpoint region from deleted and duplicated
mtDNA independently, we isolated the deleted and duplicated
mtDNA by gel fractionation of a PstI-digested total
DNA. The breakpoint was located at
mtDNA positions 5788 and 15,448 for both duplicated and deleted molecules. Our study reinforces the concept that endocrinopathies other than diabetes can be associated with a duplication of
mtDNA and gives additional support to the hypothesis that the duplication and deletion of
mtDNA are generated from the same recombination event.