Next generation sequencing in family with MNGIE syndrome associated to optic atrophy: Novel homozygous POLG mutation in the C-terminal sub-domain leading to mtDNA depletion

Introduction Mitochondrial diseases are a group of disorders caused mainly by the impairment of the mitochondrial oxidative phosphorylation process, due to mutations either in the mitochondrial or nuclear genome. Among them, the mitochondrial neuro-gastrointestinal encephalo-myopathy (MNGIE) syndrome affects adolescents or young adults, and is mostly caused by TYMP mutations encoding a cytosolic thymidine phosphorylase (TP). Patients and methods The present study reports the molecular investigation by next-generation re-sequencing of 281 nuclear genes, encoding mitochondrial proteins, of consanguineous family including two individuals with MNGIE syndrome associated to optic atrophy. Bioinformatic analysis was also performed in addition to mtDNA deletion screening and mtDNA copy number quantification in blood of the two patients which were carried out by solf clipping program and qPCR respectively. Results Next-generation re-sequencing revealed a novel homozygous c.2391G > T POLG mutation (p.M797I) co-occurring with the hypomorphic c.1311A > G OPA1 variant (p.I437M). Analysis of the mitochondrial genome in the two patients disclosed mtDNA depletion in blood, but no deletion. Bio-informatics investigations supported the pathogenicity of the novel POLG mutation that is located in the C-terminal subdomain and might change POLG 3D structure, stability and function. Conclusion The novel homozygous p.M797I POLG mutation is responsible for MNGIE combined to optic atrophy and mtDNA depletion in the two patients

Immune Activation Reduces Sperm Quality in the Great Tit

Mounting an immune response against pathogens incurs costs to organisms by its effects on important life-history traits, such as reproductive investment and survival. As shown recently, immune activation produces large amounts of reactive species and is suggested to induce oxidative stress. Sperm are highly susceptible to oxidative stress, which can negatively impact sperm function and ultimately male fertilizing efficiency. Here we address the question as to whether mounting an immune response affects sperm quality through the damaging effects of oxidative stress. It has been demonstrated recently in birds that carotenoid-based ornaments can be reliable signals of a male's ability to protect sperm from oxidative damage. In a full-factorial design, we immune-challenged great tit males while simultaneously increasing their vitamin E availability, and assessed the effect on sperm quality and oxidative damage. We conducted this experiment in a natural population and tested the males' response to the experimental treatment in relation to their carotenoid-based breast coloration, a condition-dependent trait. Immune activation induced a steeper decline in sperm swimming velocity, thus highlighting the potential costs of an induced immune response on sperm competitive ability and fertilizing efficiency. We found sperm oxidative damage to be negatively correlated with sperm swimming velocity. However, blood resistance to a free-radical attack (a measure of somatic antioxidant capacity) as well as plasma and sperm levels of oxidative damage (lipid peroxidation) remained unaffected, thus suggesting that the observed effect did not arise through oxidative stress. Towards the end of their breeding cycle, swimming velocity of sperm of more intensely colored males was higher, which has important implications for the evolution of mate choice and multiple mating in females because females may accrue both direct and indirect benefits by mating with males having better quality sperm

A randomised control trial examining the effect of an antioxidant (Menevit) on pregnancy outcome during IVF-ICSI treatment

The definitive version is available at www.blackwell-synergy.comBackground: Evidence has accumulated supporting the role of reactive oxygen species (ROS) in the pathogenesis of sperm dysfunction among men with infertility. Damage to sperm DNA by ROS can lead to failure of conception, miscarriage or potentially even childhood cancer. The objective of this study was to examine the effect of male antioxidant treatment on embryo quality and pregnancy outcome during in vitro fertilisation-intracytoplasmic sperm injection (IVF-ICSI) treatment. Methods: Sixty couples with severe male factor infertility were enrolled in a prospective randomised double-blind placebo-controlled trial. Male participants were randomly assigned to take either one capsule per day of the Menevit antioxidant or an identical in appearance placebo for three months prior to their partner's IVF cycle. The primary outcome was cleavage stage embryo quality and the secondary outcomes were oocyte fertilisation rate, pregnancy rates and treatment side-effects. Approval by the local Human Research Ethics Committee was obtained prior to the commencement of this study. Results: The antioxidant group recorded a statistically significant improvement in viable pregnancy rate (38.5% of transferred embryos resulting in a viable fetus at 13 weeks gestation) compared to the control group (16% viable pregnancy). No significant changes in oocyte fertilisation rate or embryo quality were detected between the antioxidant and the placebo groups. Side-effects on the Menevit antioxidant were rare (8%) and mild in nature. Conclusions: The Menevit antioxidant appears to be a useful ancillary treatment that significantly improves pregnancy rates in couples undergoing IVF-ICSI treatment for severe male factor infertility.Kelton Tremellen, George Miari, David Froiland and Jeremy Thompso