Novel mtDNA Imparts the Connective Tissue Disorder of a Tourette Pedigree

Mitochondrial dysfunction is associated with a range of clinical manifestations including neuropsychiatric and metabolic disorder. Here, we reanalyzed a family with an L-Histidine Decarboxylase (HDC) variant previously linked to Tourette syndrome but with associated connective tissue and metabolic features of unknown etiology. We identified a mitochondrial haplogroup J-defining mutation on the haplogroup H background that functionally interacts with the L-Histidine Decarboxylase variant via calcium homeostasis. Our findings establish how a common mtDNA variant on a different mtDNA background can result in mitochondrial dysfunction, demonstrate a role for histaminergic signaling in modifying mitochondrial phenotypes, and link mitochondria dysfunction to connective tissue phenotypes. ### Competing Interest Statement Douglas C. Wallace is part of the scientific advisory boards for: Pano Therapeutics Medical Excellence Capital. Neither of these companies have had any involvement in this research or relate to this manuscript.