CODAS syndrome is a multi-system developmental disorder characterized by cerebral, ocular, dental, auricular, and skeletal anomalies. Using whole-exome and Sanger sequencing, we identified four LONP1 mutations inherited as homozygous or compound-heterozygous combinations among ten individuals with CODAS syndrome. The individuals come from three different ancestral backgrounds (Amish-Swiss from United States, n = 8; Mennonite-German from Canada, n = 1; mixed European from Canada, n = 1). LONP1 encodes Lon protease, a homohexameric enzyme that mediates protein quality control, respiratory-complex assembly, gene expression, and stress responses in mitochondria. All four pathogenic amino acid substitutions cluster within the AAA(+) domain at residues near the ATP-binding pocket. In biochemical assays, pathogenic Lon proteins show substrate-specific defects in ATP-dependent proteolysis. When expressed recombinantly in cells, all altered Lon proteins localize to mitochondria. The Old Order Amish Lon variant (LONP1 c.2161C>G[p.Arg721Gly]) homo-oligomerizes poorly in vitro. Lymphoblastoid cell lines generated from affected children have (1) swollen mitochondria with electron-dense inclusions and abnormal inner-membrane morphology; (2) aggregated MT-CO2, the mtDNA-encoded subunit II of cytochrome c oxidase; and (3) reduced spare respiratory capacity, leading to impaired mitochondrial proteostasis and function. CODAS syndrome is a distinct, autosomal-recessive, developmental disorder associated with dysfunction of the mitochondrial Lon protease.

Shorter telomeres in sperm may be one of the causative factors responsible for male infertility, but further detailed studies are needed to confirm these findings.

Telomeres, noncoding hexameric tandem repeats located at the ends of chromosomes, maintain chromosome stability and genome integrity. These guanine-rich repeats are highly conserved during evolution, and their role is dependent on their length and structure. They have multiple functions, including regulating the reproductive lifespan by mediating synapsis and homologous recombination of the chromosomes. Short telomeres result in meiotic arrest, segregation abnormalities and dysjunction, which lead to an increased incidence of aneuploid germ cells. In addition, shortened telomeres in men result in apoptosis of germ cells, whereas, in women, they result in meiotic arrest. In somatic cells, telomere shortening occurs at each consecutive round of replication, which induces senescence in vitro and in vivo. However there is a 2-fold elongation of telomeres during spermatogenesis. Spermatozoa, are terminally differentiated cells, have longer telomeres than spermatogonia and pachytene spermatocytes. In addition to genetic factors, lifestyle factors and psychological stress also play crucial role in modulating telomere length. Because not much is known about its role in reproduction, we focused this review on the function, structure and length dynamics of the telomere in the reproductive process.

Mitochondrial transcription factor A (TFAM) is essential for the maintenance, expression and transmission of mitochondrial DNA (mtDNA). However, mechanisms for the post-translational regulation of TFAM are poorly understood. Here, we show that TFAM is lysine acetylated within its high-mobility-group box 1, a domain that can also be serine phosphorylated. Using bulk and single-molecule methods, we demonstrate that site-specific phosphoserine and acetyl-lysine mimics of human TFAM regulate its interaction with non-specific DNA through distinct kinetic pathways. We show that higher protein concentrations of both TFAM mimics are required to compact DNA to a similar extent as the wild-type. Compaction is thought to be crucial for regulating mtDNA segregation and expression. Moreover, we reveal that the reduced DNA binding affinity of the acetyl-lysine mimic arises from a lower on-rate, whereas the phosphoserine mimic displays both a decreased on-rate and an increased off-rate. Strikingly, the increased off-rate of the phosphoserine mimic is coupled to a significantly faster diffusion of TFAM on DNA. These findings indicate that acetylation and phosphorylation of TFAM can fine-tune TFAM–DNA binding affinity, to permit the discrete regulation of mtDNA dynamics. Furthermore, our results suggest that phosphorylation could additionally regulate transcription by altering the ability of TFAM to locate promoter sites.

Sperm DNA integrity is a prerequisite for normal spermatozoal function. The aim of the study was to evaluate the role of sperm chromatin damage, its cut-off level and its effect on sperm parameters in men with idiopathic infertility by analyzing 100 idiopathic infertile men and 50 fertile controls. Semen samples were analyzed as per WHO 1999 guidelines and sperm chromatin structure assay (SCSA) was applied to measure DNA fragmentation index (DFI) in sperm. The mean DFI of infertile men (35.75) was significantly (P < .0001) higher as compared to controls (26.22). The threshold level of 30.28% was obtained as cut-off value to discriminate infertile men from fertile controls. Sperm count, forward motility, and normal morphology found to be negatively associated with DFI in overall study subjects. Infertile men with severe oligozoospermia had higher mean DFI (40.01 ± 11.31) than infertile men with oligozoospermia (35.11 ± 10.05) and normal sperm count (33.99 ± 9.96). Moreover 64% of infertile men have DFI > 30 against 6% of fertile controls (P < .0001). Higher sperm DNA fragmentation may be the underlying cause for poor semen quality in idiopathic infertile men and the threshold value of 30.28% is a clear discriminator to distinguish infertile men from fertile men of Indian population. Thus, DFI is a good prognostic marker as cases with higher sperm DFI may have poor success rate even after assisted conception and may experience recurrent pregnancy loss (RPL) and should be counseled accordingly.

Other than chromosomal anomalies, sperm DNA fragmentation and seminal OS may be the underlying pathology in RSA, thus screening for seminal ROS levels and DNA fragmentation has diagnostic and prognostic capabilities.

Purpose Telomere length plays a significant role in various disorders; however, its role in idiopathic recurrent pregnancy loss (iRPL) is not known. The objective of this study was to assess telomere length in peripheral blood leukocytes in couples experiencing unexplained recurrent pregnancy loss (iRPL). Methods The study included 25 couples experiencing iRPL and 20 controls. The mean relative telomere length was measured by quantitative Real Time PCR (Q-PCR) based assay, which measures the average ratio of telomere repeat copy number to a single copy gene (36B4) copy number (T/S ratio) in each sample. Results The relative leukocyte mean telomere length (T/S) in both men and women from iRPL group was significantly lower (p<0.05) when compared to controls. A significant (P<0.05) negative correlation was found between age and leukocyte telomere length (T/S ratio). Among the sperm parameters seminal volume was found to be negatively (r = −0.4679) associated with the telomere T/S ratio. The DNA fragmentation index of sperm showed positive correlation (r=0.4744) with telomere length. In this preliminary study, we found that shorter telomere length in both men and women may be associated with early pregnancy loss. Conclusion In conclusion, shorter telomere length in both male and female partners appears to play a role in the idiopathic recurrent pregnancy loss. Loss of telomeric DNA due to oxidative stress needs further analysis. Analysis of telomere length in germ cells are needed to further substantiate the findings of this study.

Sperm function is essential for fertilization and embryogenesis yet semen contain a heterogeneous population of sperm. This study was designed to evaluate two different sperm populations separated by the density gradient method. Semen from 25 idiopathic normozoospermic infertile men was processed by double density gradient centrifugation and evaluated for sperm present in the 50% (upper) layer and the 90% (lower) layer for reactive oxygen species (ROS), sperm chromatin integrity, and morphology. The population of sperm in the 90% layer showed significantly lower ROS levels (22.90 (0.92, 85.32) vs. 382.03 (158.30, 1409.51) and lower DNA fragmentation index (DFI) (24.26 (22.54, 25.50) vs. 29.93 (28.48, 31.25) and higher number of sperm with normal morphology (55 (45.0, 60.0) vs. 32.5 (20, 40) compared to sperm in the 50% layer. However, in the original raw semen, sperm DFI (27.02 (26.19, 27.76)) and percentage high DNA stainability (% HDS) (3.1 (2.40, 3.78)) cells were significantly higher compared to the 90% layer population. Density gradient separation of the sperm subpopulation from the original semen favors the selection of sperm with genome integrity, low levels of ROS, and normal morphology. Therefore presence of pathological sperm in the semen may disrupt the function of normal spermatozoa, and hence the selection of the normal sperm subpopulation may be a better candidate for assisted conception. Further studies are required to evaluate the gradient separated sperm population in assisted reproductive techniques (ART).