Mitochondrial DNA variations are associated with recurrent pregnancy loss

Preimplantation genetic testing as a preventive strategy for the transmission of mitochondrial DNA disorders

Mitochondrial diseases are distinct types of metabolic and/or neurologic abnormalities that occur as a consequence of dysfunction in oxidative phosphorylation, affecting several systems in the body. There is no effective treatment modality for mitochondrial disorders so far, emphasizing the clinical significance of preventing the inheritance of these disorders. Various reproductive options are available to reduce the probability of inheriting mitochondrial disorders, including in vitro fertilization (IVF) using donated oocytes, preimplantation genetic testing (PGT), and prenatal diagnosis (PND), among which PGT not only makes it possible for families to have genetically-owned children but also PGT has the advantage that couples do not have to decide to terminate the pregnancy if a mutation is detected in the fetus. PGT for mitochondrial diseases originating from nuclear DNA includes analyzing the nuclear genome for the presence or absence of corresponding mutations. However, PGT for mitochondrial disorders arising from mutations in mitochondrial DNA (mtDNA) is more intricate, due to the specific characteristics of mtDNA such as multicopy nature, heteroplasmy phenomenon, and exclusive maternal inheritance. Therefore, the present review aims to discuss the utility and challenges of PGT as a preventive approach to inherited mitochondrial diseases caused by mtDNA mutations.

Complete mitochondrial genomes of patients from Thailand with cardiovascular diseases

Several previous studies have reported that both variation and haplogroups of mitochondrial (mt) DNA were associated with various kinds of diseases, including cardiovascular diseases, in different populations, but such studies have not been carried out in Thailand. Here, we sequenced complete mtDNA genomes from 82 patients diagnosed with three types of cardiovascular disease, i.e., Hypertrophic Cardiomyopathy (HCM) (n = 26), Long Q-T Syndrome (LQTS) (n = 7) and Brugada Syndrome (BrS) (n = 49) and compared these with 750 previously published mitogenome sequences from interviewed normal individuals as a control group. Both patient and control groups are from the same geographic region of northeastern Thailand. We found 9, 2, and 5 novel mutations that were not both damaging and deleterious in HCM, LQTS, and BrS patients, respectively. Haplogroup R9c was significantly associated with HCM (P = 0.0032; OR = 62.42; 95%CI = 6.892-903.4) while haplogroup M12b was significantly associated with LQTS (P = 0.0039; OR = 32.93; 95% CI = 5.784-199.6). None of the haplogroups was found to be significantly associated with BrS. A significantly higher density of mtDNA variants in the rRNA genes was found in patients with HCM and BrS (P < 0.001) than in those with LQTS or the control group. Effects of detected SNPs in either protein coding or tRNA genes of all the mitogenome sequences were also predicted. Interestingly, three SNPs in two tRNA genes (MT-TA m.5618T>C and m.5631G>A heteroplasmic variants in two BrS patients and MT-TQ m.4392C>T novel homoplasmic variant in a HCM patient) were predicted to alter tRNA secondary structure, possibly leading to abnormal tRNA function.

m.4216 T > C polymorphism in JT cluster determines a lower pregnancy rate in response to controlled ovarian stimulation treatment

PURPOSE

To analyze the influence of Caucasian mitochondrial haplogroups on controlled ovarian stimulation outcome (COS), embryo (E), and pregnancy success.

METHODS

In a Caucasian population (n = 517) undergoing COS, mitochondrial haplogroups and physiological parameters were determined. Patients were classified, according to Bologna criteria, as good (>3)/poor ≤3) responder, on dependence of recruited oocytes (RO), and in pregnancy/non-pregnancy groups. Haplogroups were determined by sequencing mitochondrial hypervariable sequence I and confirmed by polymerase chain reaction (PCR), followed by restriction fragment length polymorphisms (RFLP).

RESULTS

The rank of total dose of FSH (TD FSH) was similar in all clusters/haplogroups, except in JT, which is narrower (950-3,650 IU), particularly in T (1,350-3,650 IU). The statistical analysis showed higher RO and E in JT when compared to U, although it was only Uk which accumulated significantly in pregnancy respect to JT. Pearson's correlations between TD FSH and RO showed negative statistical significance in all population (P = 0.001), H (P = 0.03), JT (P = 0.01), and T (P = 0.03). The percentage of contribution of TD FSH on RO was almost nine times in the JT cluster as compared to all population one.

CONCLUSIONS

JT cluster shows a different influence of TD FSH on RO. JT cluster shows higher RO and E than U, but it is Uk which exhibits a significant higher pregnancy rate than JT. The negative influence of the JT cluster on pregnancy success strongly suggests that the m.4216 T > C polymorphism could be responsible.

Depression, mitochondrial bioenergetics, and electroconvulsive therapy: a new approach towards personalized medicine in psychiatric treatment - a short review and current perspective

Major depressive disorder (MDD) is a globally occurring phenomenon and developed into a severe socio-economic challenge. Despite decades of research, the underlying pathophysiological processes of MDD remain incompletely resolved. Like other mental disorders, MDD is hypothesized to mainly affect the central nervous system (CNS). An increasing body of research indicates MDD to also change somatic functioning, which impairs the physiological performance of the whole organism. As a consequence, a paradigm shift seems reasonable towards a systemic view of how MDD affects the body. The same applies to treatment strategies, which mainly focus on the CNS. One new approach highlights changes in the bioenergetic supply and intracellular network dynamics of mitochondria for the pathophysiological understanding of MDD. Mitochondria, organelles of mostly all eukaryotic cells, use carbon compounds to provide biochemical energy in terms of adenosine triphosphate (ATP). ATP is the bioenergetic currency and the main driver for enzymatic activity in all cells and tissues. Clinical symptoms of MDD including fatigue, difficulties concentrating, and lack of motivation were reported to be associated with impaired mitochondrial ATP production and changes in the density of the mitochondrial network. Additionally, the severity of these symptoms correlates negatively with mitochondrial functioning. Psychotherapy, antidepressant medication, and electroconvulsive therapy (ECT), a method used to treat severe and treatment-resistant forms of MDD, achieve robust antidepressant effects. The biological mechanisms beyond the treatment response to antidepressant strategies are partially understood. Here, mitochondrial functioning is discussed as a promising new biomarker for diagnosis and treatment effects in MDD.