m. 10010T >C Mitochondrial Disease: A Case Report With Hypoparathyroidism and Review of the Literature

Mitochondria are essential intracellular organelles that play a critical role in cellular metabolism, including the regulation of intracellular calcium signaling. Advances in genomic sequencing have facilitated the identification of rare pathogenic mitochondrial DNA (mtDNA) genetic variants in patients with unexplained endocrine disorders. We present a case report of a woman diagnosed with the rare mtDNA variant m.10010T>C. The case report includes a detailed clinical evaluation, heteroplasmy measurements across several tissues, and a review of previously published cases of patients heteroplasmic for the m.10010T>C variant. The patient developed myopathy and exercise‐induced dyspnoea at 24 years of age. Nineteen years later, progressive muscle symptoms were accompanied by elevated blood lactate and hypoparathyroidism. Muscle biopsy revealed abnormal mitochondrial morphology with cytochrome C oxidase‐negative fibers and deficiencies in respiratory chain Complexes I, II, and IV. Genetic analysis identified the m.10010T>C variant with 95% heteroplasmy in the muscle biopsy, 20% in urine, 4% in buccal mucosa, and undetectable in blood (< 1%). We report the first case of a m.10010T>C carrier with hypoparathyroidism, which is a rare and unexplained finding in mitochondrial disorders that may exacerbate myopathy.