Letter to the Editor:
With interest we read the article by Billing-Ross et al. [1] about 193 patients with chronic fatigue syndrome (CFS) diagnosed according to the Fukuda or Canadian Consensus criteria and undergoing sequencing of the mtDNA, the DePaul Symptom questionnaire and the Medical Outcome Survey Short Form-36. The study showed that CFS is associated with mtDNA haplogroups J, U and H, that 8 mtDNA single nucleotide polymorphisms (SNPs) were associated with 16 symptom categories, and that three haplogroups were associated with six symptom categories [1]. We have the following comments and concerns.
The main limitation of this study is that only the mtDNA was investigated for sequence variants. Since it is well-known that mitochondrial disorders (MIDs) may be also caused by mutations in nDNA-located genes, particularly in children [2], disease-causing mutations or SNPs facilitating the development of CFS may have been missed. Furthermore, MIDs may not only be due to respiratory chain dysfunction but also due to disruption of other mitochondrial pathways, such as the beta-oxidation, the hem synthesis, the calcium handling, the coenzyme-Q metabolism, or the urea cycle. There is also consensus that investigations of mtDNA mutations or SNPs in mtDNA from lymphocytes may not be constructive since some mutations may not be present or heteroplasmy rates may be lower than in more severely affected tissues [3].
You can read the rest of this letter here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4912808/
Source: Finsterer J, Zarrouk-Mahjoub S. Is chronic fatigue syndrome truly associated with haplogroups or mtDNA single nucleotide polymorphisms? J Transl Med. 2016 Jun 18;14(1):182. doi: 10.1186/s12967-016-0939-0. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4912808/ (Full article)