We thank Professor Koch for his additional comments on our article from an endocrinologist’s perspective (1). We did point out the extreme phenotypic heterogeneity of mitochondrial disorders; because of restricted space we were not able to explain partial aspects in any detail. Ultimately one might say that endocrine dysfunction is a variable characteristics of different mitochondrial disorders and can manifest as diabetes mellitus, growth hormone deficiency, hypogonadism, hypoparathyroidism, as well as thyroid or adrenal dysfunction (2). It is important to detect these endocrine disorders as symptomatic treatment is often a possibility, which in turn can improve patients’ quality of life.
We also thank the correspondent for the important mention of the recently published consensus paper regarding tumor screening in asymptomatic carriers of SDHx mutations (3). Pyruvate therapy to increase insulin secretion in mitochondrial diabetes mellitus has so far been described in one patient only—larger studies are still needed. And while resveratrol has yielded promising preclinical results, it has not yet been investigated in clinical studies in mitochondrial disorders. Statins should indeed be given with caution, but on the other hand they should not be withheld from patients with mitochondrial disorders in case of a clear cardiovascular indication—in this setting, an individual risk-benefit assessment should be carried out. We definitely support the recommendation to avoid fasting and dehydration.
Footnotes
Conflict of interest statement
Prof. Klopstock received third-party funding to conduct clinical trials from Santhera Pharmaceuticals, GenSight Biologics, Khondrion, and Stealth BioTherapeutics. He is chairman of the non-profit association Deutsches mitoNET e. V., which received donations from Santhera Pharmaceuticals and GenSight Biologics. He received consulting fees from Santhera Pharmaceuticals, GenSight Biologics, Chiesi GmbH, and Pretzel Therapeutics. For lectures he received speaker’s fees from Santhera Pharmaceuticals, GenSight Biologics, and Chiesi GmbH. In addition, the abovementioned companies partially reimbursed congress fees as well as travel and accommodation costs.
References
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