Search Results (139)

Aphids are important agricultural pests that interact with diverse bacterial taxa living within or associated with their bodies. Some bacteria, such as the obligate symbiont Buchnera aphidicola, provide essential nutritional functions and are predominantly inherited vertically, whereas other aphid-associated bacteria may have more variable distributions and ecological roles. In this study, we investigated patterns of association between aphid evolutionary relationships and selected bacterial taxa. Aphids were identified using morphological characteristics and mitochondrial cytochrome c oxidase subunit I (COI) sequences, and host phylogenetic relationships were reconstructed using mitochondrial DNA data. We then compared the host phylogeny with that of the obligate symbiont Buchnera aphidicola based on 16S rRNA sequences and screened aphid specimens for selected aphid-associated bacteria (Wolbachia, Pantoea, and Arsenophonus) using diagnostic PCR assays. The host and Buchnera phylogenies showed significant global congruence, consistent with a strong long-term host-associated evolutionary relationship and predominantly vertical inheritance of Buchnera. In contrast, the selected aphid-associated bacteria showed heterogeneous detection patterns across the sampled aphid taxa. Pantoea was detected relatively frequently and across a broad range of sampled hosts, whereas Wolbachia and Arsenophonus showed more variable and restricted detection patterns. Given the small and uneven sample sizes among aphid species, these findings are interpreted as descriptive screening patterns rather than species-level prevalence estimates. Overall, the results highlight contrasting patterns of host-associated evolution between Buchnera and other aphid-associated bacteria and provide a basis for further investigation of the ecological and evolutionary processes underlying these associations. Full article

SLC25A4, solute carrier family 25 member 4, gene is a member of the mitochondrial carrier subfamily within the solute carrier protein family. Pathogenic variants in SLC25A4 are associated with a spectrum of mitochondrial disorders that exhibit variable inheritance patterns and clinical manifestations. Specifically, dominantly inherited variants are typically associated with progressive external ophthalmoplegia with mitochondrial DNA deletions, recessively inherited variants are linked to myopathy and cardiomyopathy, and de novo variants can result in early-onset fatal disease presentations. In this study, we aimed to identify and characterize the disease-causing mutation(s) in a nine-year-old female patient from a consanguineous Saudi family. The patient was asymptomatic until the age of 3 years, when she presented with cardiomyopathy and myopathy. Comprehensive genetic analysis inclusive of whole exome sequencing and segregation analysis using Sanger sequencing identified an SLC25A4 variant (NM_001151.4: exon 2: c.112-1G>C) as the most likely cause of the disease. To assess transcript-level effects, we performed RT-PCR on RNA extracted from the patient’s cultured lymphoblast cell lines (LCLs) and fibroblast cell lines (FCLs). RT-PCR analysis demonstrated that the variant causes aberrant splicing, resulting in a 6 bp in-frame deletion (p.Gln37_Val38del) in the ANT1 protein. Quantitative RT-PCR demonstrated reduced SLC25A4 transcript levels in both FCLs and LCLs. Quantitative PCR analysis of mitochondrial DNA demonstrated a trend toward increased mtDNA copy number in patient-derived FCLs compared with controls, suggesting a possible compensatory response to mitochondrial dysfunction. Furthermore, Seahorse assays revealed marked reductions in both oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) in patient-derived FCLs compared with controls. These findings expand the molecular and functional spectrum of SLC25A4-associated disease and may inform clinical practice, including genetic interventions such as preimplantation genetic diagnosis, premarital genetic screening, targeted genetic counseling, and cascade testing of at-risk family members. Full article

Background/Objectives: The developmental origins of health and disease (DOHaD) theory suggests that intrauterine and early postnatal life represents a critical window for programming lifelong health trajectories and disease susceptibility in offspring. Maternal nutritional imbalance during this period is closely associated with obstetric complications and an elevated risk of metabolic disorders in children. As central metabolic hubs, mitochondria constitute a critical axis linking adverse in utero exposure to metabolic defects in offspring across generations. Methods: In this narrative review, we searched PubMed and Web of Science (up to 8 July 2026) for English-language literature linking maternal metabolic conditions and mitochondrial dysfunction. We included in vivo, in vitro, and clinical studies, explicitly excluding primary inherited mtDNA mutations and nonnutritional toxicant exposures to isolate nutritional programming effects. Results: Maternal metabolic stress induces multifaceted, tissue-specific mitochondrial alterations in the developing offspring. Rather than a uniform systemic decline, mitochondrial reprogramming exhibits profound spatial and cellular heterogeneity across critical metabolic organs, including the placenta, liver, skeletal muscle, heart, and hypothalamus. These developmental adaptations often manifest as molecular compensations, such as altered mitochondrial dynamics, perturbed biogenesis, and shifted OXPHOS capacity, ultimately leading to functional bioenergetic failure, oxidative stress, and the establishment of insulin resistance. Discussion: Organ-specific mitochondrial dysfunction drives the maternal transmission of metabolic syndrome. Targeting these mechanisms via dietary modifications, exercise, pharmacological agents, and mitochondrial transplantation offers promising strategies to rescue bioenergetics and prevent metabolic diseases in offspring. Full article

Background/Objectives: Patient registries are essential for rare disease research, yet the extensive genetic and phenotypic heterogeneity of primary mitochondrial diseases (PMDs) makes traditional registry development slow and resource-intensive. We established the MSeqDR PMD virtual registry (PMD-VR) to address this gap through systematic literature mining and semi-automated data harmonization. Methods: The PMD-VR captures, standardizes, and harmonizes published case-level PMD data using a semi-automated curation pipeline. A data transformation framework maps heterogeneous raw data terms to standardized common data elements (CDEs). A generative AI (GenAI) platform leveraging large language models (LLMs), augmented by Human Phenotype Ontology (HPO) and external biomedical knowledge sources, accelerates data transformation and generates simulated clinical reports. Results: Currently, PMD-VR contains approximately 11,000 de-identified literature-derived cases, including over 2300 Leigh syndrome spectrum (LSS), 278 MELAS, and 300 CPEO cases. The pipeline mapped 872 heterogeneous terms to 102 standardized CDEs. Pathogenicity assessments were captured for variants in over 7900 cases, including 3800 with mtDNA pathogenic or likely pathogenic variants. Modes of inheritance were inferred for 5212 cases. PMD-VR has supported ClinGen Mitochondrial Diseases Gene Curation Expert Panel (Mito-GCEP) efforts, providing phenotyped evidence for 440 curated LSS cases across 113 PMD genes. Conclusions: PMD-VR is among the largest single PMD registries, offering a scalable, web-accessible platform for generating analysis-ready cohorts from the published literature. It represents a rich resource enabling comprehensive PMD characterization with unprecedented breadth of genetic and phenotypic knowledge. Full article

Mitochondrial dysfunction and oxidative stress are increasingly recognized as key contributors to the development and progression of retinal degenerative diseases, including age-related macular degeneration and inherited retinal dystrophies. Growing evidence suggests that alterations in mitochondrial function, excessive production of reactive oxygen species, defective mitophagy, and chronic inflammatory responses are closely interconnected processes that contribute to retinal cell damage and degeneration. This review provides an overview of the current understanding of the molecular mechanisms linking mitochondrial dysfunction to retinal degeneration, with particular emphasis on the impact of oxidative stress, mitochondrial quality-control pathways, and inflammatory signaling. Available evidence indicates that mitochondrial DNA damage, impaired bioenergetics, and dysregulated mitochondrial dynamics play a crucial role in the degeneration of photoreceptors and retinal pigment epithelium cells. In turn, oxidative stress further exacerbates mitochondrial impairment, creating a self-sustaining cycle that promotes disease progression. Recent advances have also highlighted the therapeutic potential of targeting mitochondrial pathways. Although several mitochondria-directed strategies have shown encouraging results in experimental models, their translation into clinical practice remains at an early stage. Overall, the available data identify mitochondria as a promising therapeutic target and support the development of precision medicine approaches aimed at preserving retinal function and slowing disease progression in patients with retinal degenerative disorders. Full article

Human ageing and longevity are increasingly understood as biologically integrated and heterogeneous processes shaped by interactions among genetic susceptibility, epigenetic remodelling, and environmental modulation. This narrative review examines these interconnections within a nutrigenomic framework, with particular emphasis on how inherited variation and epigenetic plasticity may influence responses to ageing-related interventions. A structured literature search was conducted in PubMed, Scopus, Web of Science, and Embase, focusing on English-language studies published during the last 10 years. The review was organized into three major domains: (i) genetic determinants of longevity, (ii) epigenetic mechanisms of ageing, and (iii) intervention-responsive pathways relevant to precision geroscience. Current evidence supports a polygenic model of longevity in which loci such as FOXO3 and APOE show the most consistent human associations, while telomere maintenance, insulin/IGF-1 and mTOR signalling, sirtuins, Klotho, inflammatory mediators, and DNA repair remain biologically important but variably supported at the variant level. Epigenetic mechanisms, including DNA methylation drift, epigenetic clocks, histone modifications, chromatin remodelling, heterochromatin loss, and non-coding RNA regulation, provide an environmentally responsive interface linking genetic background to ageing phenotypes. Nutritional, pharmacological, behavioural, and circadian interventions converge on overlapping molecular pathways involving AMPK, mTOR, FOXO, sirtuins, autophagy, mitochondrial maintenance, and inflammatory signalling, although human evidence remains heterogeneous and biomarker modulation should not be equated with clinically meaningful slowing of organismal ageing. Overall, this review highlights the value of integrating genetics, epigenetics, and intervention biology to support a more cautious and translationally relevant model of healthy ageing. It also underscores the need for precision nutrigeroscience approaches that account for tissue context, baseline physiology, and inter-individual molecular variability. Full article

Mitochondrial DNA (mtDNA) analysis is a fundamental tool in forensic genetics, particularly when biological samples exhibit severe degradation or low nuclear DNA content. Its unique biological characteristics, such as a high copy number per cell, strict matrilineal inheritance, and lack of recombination, enable human identification and reconstruction of maternal lineages in complex contexts, including disaster victim identification, historical cases, and missing persons investigations. This narrative review examines contemporary methodological approaches for investigating the human mitogenome. We discuss recent advancements in extraction and enrichment techniques, emphasizing their efficacy in reducing the interference of nuclear mitochondrial DNA sequences (NUMTs) and enhancing the recovery of informative fragments. Moreover, the shift from traditional Sanger sequencing to Massive Parallel Sequencing (MPS) is examined, as MPS has markedly enhanced the sensitivity and capability of contemporary methods to detect low-frequency heteroplasmies. Additionally, the advent of Third-Generation Sequencing (TGS), exemplified by nanopore platforms, is evaluated, which facilitates the reading of full-length native molecules without the biases introduced by PCR amplification. Despite the interpretive challenges posed by heteroplasmy, contamination, and limitations in population databases, ongoing methodological advances in mitochondrial DNA analysis continue to strengthen its reliability and expand its potential in forensic genetics. Full article

Background/Objectives: To assess the knowledge, attitudes, and practices of ophthalmologists in Saudi Arabia towards genomic medicine and genetic testing, in light of the growing significance of genomics in ophthalmology and the national transition towards precision medicine. Methods: A cross-sectional, questionnaire-based survey was conducted among ophthalmologists, including consultants, specialists, fellows, and residents, across Saudi Arabia. The questionnaire included four domains: demographics, knowledge of genomic principles and gene therapy, self-rated confidence in genetic tasks (scored 1–10), and attitudes toward genetic testing. Data were analyzed using descriptive and inferential statistics, with subgroup comparisons performed using chi-square tests and t-tests/ANOVA. Results: A total of 115 ophthalmologists participated (46% male, 54% female; mean age 34 years; mean post-board experience 4 years). Most were consultants (40%) and practiced in Riyadh (52%). Knowledge was variable: 92% correctly identified human chromosome count, and 99% recognized autosomal recessive inheritance, but only 9% answered DNA base-pairing correctly, and 54% recognized mitochondrial inheritance. Confidence was highest for referral to specialists (mean 7.3/10) and lowest for test selection and counseling (4.7/10). The internet was the primary knowledge source among our sample (65%). The majority of individuals had positive attitudes towards genomic medicine: 90% believed testing was beneficial, 89% considered it enhanced health outcomes, and 89% indicated they would undergo testing themselves. On the other hand, 77% indicated difficulty in access, 91% strongly concurred on the significance of privacy and confidentiality, and more than half expressed concerns regarding misuse and bias. Conclusions: Ophthalmologists in Saudi Arabia acknowledge the importance of genetics. Yet, there are substantial gaps in knowledge and familiarity with genomic medicine and genetic testing. To overcome these challenges, it is essential to integrate genetics into ophthalmology curricula. Full article

Fanconi anemia (FA) is a rare inherited disorder classically defined by defective DNA interstrand crosslink repair, leading to bone marrow failure and cancer predisposition. Increasing evidence indicates that FA pathophysiology extends beyond genomic instability to include mitochondrial dysfunction, oxidative stress, and impaired antioxidant responses. Across multiple cellular models and patient-derived samples, FA cells display altered mitochondrial bioenergetics, increased reactive oxygen species (ROS) production, and defective activation of redox-adaptive pathways, contributing to cumulative damage to DNA, lipids, and proteins. These alterations are particularly relevant in hematopoietic stem and progenitor cells, where metabolic stress and redox imbalance amplify stem cell exhaustion. Current data support a bidirectional interplay in which mitochondrial dysfunction and oxidative stress act mainly as secondary but amplifying factors of the primary DNA repair defect, establishing pathogenic feedback loops. Preclinical studies suggest that modulation of redox balance and mitochondrial function may improve cellular homeostasis, and early clinical investigations of antioxidant strategies indicate acceptable safety and measurable effects on oxidative biomarkers. However, clinical evidence remains limited and heterogeneous, with uncertain impact on long-term disease progression. Moreover, most mechanistic insights derive from in vitro or patient-derived models, while animal models and longitudinal clinical studies remain insufficient. Overall, a more integrated and translational framework is needed to clarify causality, validate biomarkers, and define the therapeutic potential of targeting metabolic and redox pathways in FA. Full article

Background: Wolfram syndrome (WFS) is a rare neurodegenerative disease that is genetically determined and inherited in an autosomal recessive manner. Although the first clinical symptom appearing in early childhood is diabetes mellitus, subsequent symptoms are associated with optic nerve atrophy, followed by central nervous system atrophy. Methods: The aim of the study was to analyse magnetic resonance images (MRI) of the brain in combination with single-voxel magnetic resonance spectroscopy (MRS) and to assess the copy number of mitochondrial DNA (mtDNA-CN) in 10 patients with WFS compared with a control group of 17 healthy individuals. Results: A significant decrease in the amount of selected metabolites was observed in WFS patients compared to controls in all assessed brain regions (pons, cerebellum, white matter, thalamus, and hippocampus). For three metabolites, Glutamate (Glu), Glutamate + Glutamine (Glx) and total N-acetylaspartate (TNAA), significant differences in concentrations were found between the study groups in almost all matrices evaluating specific areas of the brain (p < 0.011), with the exception of a trend toward reduced TNAA in the hippocampus (p = 0.065). In addition, patients with WFS had a significant decrease in the mitochondrial-to-nuclear DNA ratio compared to controls (p < 0.0003). Some metabolites, such as N-acetylaspartate and total N-acetylaspartate, showed strong correlations with specific regions of the visual pathway on MRI scans in patients with WFS. Conclusions: Selected brain metabolites and mtDNA-CN may become potential markers of WFS, and the results of this study may be used to define indicators for future therapeutic strategies. Full article

Introduction: Parkinson’s disease (PD) is a prevalent neurodegenerative disorder, with several proposed pathogenic mechanisms. Given the established role of mitochondrial dysfunction in PD, this study seeks to investigate the enrichment of rare genetic variants tied to mitochondrial metabolism in cases of early-onset and familial PD. Methods: We performed a retrospective analysis on 248 early-onset and familial PD patients and 1622 control individuals. We assessed both pathway-level and gene-level burden of germline rare variants detected using exome sequencing in 467 nuclear genes related to mitochondrial metabolism. Results: Gene-set mutation burden analysis indicated an increased burden in genes associated with mtDNA maintenance. In addition, gene-level analysis identified a possible association between PD and rare variant burden in 14 mitochondrial metabolism-related genes under dominant or recessive inheritance models. Conclusions: Our findings support a potential contribution of rare germline variants affecting mitochondrial metabolism to the susceptibility in early-onset and familial PD. Full article

Mitochondria play a fundamental role in human reproduction by supplying the energy required for key early reproductive processes. As mitochondrial Deoxyribonucleic acid (mtDNA) is maternally inherited, pathogenic mutations can lead to multisystem disorders that are transmitted to offspring. Mitochondrial replacement therapy (MRT) has emerged as a promising assisted reproductive approach to prevent the transmission of pathogenic mtDNA by replacing defective mitochondria with healthy donor mitochondria. There have been recent reports of successful MRT in humans. However, MRT remains a relatively new procedure and needs further experiments to establish its long-term safety and effectiveness. Overall, mitochondrial replacement therapy holds significant promise in helping families build healthier futures. This review explores the evolution of mitochondrial DNA modification in reproductive cells and addresses the associated ethical considerations, including acceptable clinical indications, reproductive choices, and long-term considerations for affected children. Full article

Background: Diabetes mellitus is characterized by elevated blood sugar due to absolute or relative insulin deficiency. Diabetes is classified as type 1 (T1D) or type 2 diabetes (T2D), gestational diabetes, and other types, such as monogenic diabetes, exocrine pancreatic disorders, and medication-induced diabetes. Objectives: This review article provides an overview of diabetes genetics, covering polygenic, monogenic, and syndromic forms of the disorder with emphasis on aspects to help clinicians in diagnosis, management, and counseling, but also to foster valuable knowledge for diabetic researchers in identifying phenotypes that will help inform gene discovery. Key Findings: Most cases of T1D and T2D are polygenic with environmental triggers. T1D results from autoimmune destruction of pancreatic beta cells leading to absolute insulin deficiency. Genetic studies of T1D have focused on the identification of loci associated with increased susceptibility to T1D. Early studies showed a linkage between T1D and several human leukocyte antigen (HLA) susceptibility loci on chromosome 6. Genome-wide association studies (GWAS) have identified more than 100 HLA- and non-HLA loci that increase susceptibility to T1D. It has been well established that a substantial portion of the genetic risk for T1D is encoded in the HLA locus. The non-HLA loci INS, CTLA4, IL2RA, IFIH1, and PTPN22 make moderate contributions to T1D risk. Many other non-HLA loci have small effects to the phenotype and are relevant to autoimmunity, but they are yet to be identified. T2D, on the other hand, is associated with obesity and insulin resistance with relative insulin deficiency. Thousands of gene variants that are common and contribute small effects have also been identified through GWAS to contribute to T2D risk, but the rarer variants may confer significant risk to an individual’s risk. Common variants in the TCF7L2 locus consistently carry one of the largest risks associated with T2D with a reported 1.7-fold disease odds for homozygous carriers. The usefulness of individual variants for genetic counseling in the common forms of diabetes has been limited in clinical settings in the past. The development of polygenic risk scores (PRS) and partitioned polygenic risk scores (PPRS), statistics derived from GWAS, are being used to predict and classify diabetes. The performance of PRS and PPRS varies by ancestry and type of diabetes. The PRS performs better with T1D, with an area under the curve and receiver operating characteristics (AUC-ROC) ranging from 0.87 to 0.93, compared to 0.72–0.75 for T2D. The genetic architecture of T2D is markedly more polygenic than T1D, and the PPRS has been useful in assessing risk in that setting. Monogenic diabetes comprises several dysglycemic disorders that include neonatal diabetes, maturity-onset diabetes of the young (MODY), and other genetic syndromes that have diabetes either as an associated finding and/or as a complication. Some of the monogenic diabetes gene variants have incomplete penetrance and variable expressivity leading to different ages of onset and variable presentation even within the same family. Hence some patients with these conditions have been previously diagnosed as having T1D or T2D. Many monogenic disorders follow Mendelian inheritance patterns, so genetic counseling is relatively straightforward if pathogenic variants are found to be inherited from a parent. Counseling for forms of diabetes due to maternally inherited mitochondrial cytopathies, such as MELAS and Kearns–Sayres syndrome, is not straightforward due to the occurrence of two or more populations of genetically distinct mitochondrial DNAs in the cells (heteroplasmy); the higher the percent of pathogenic variants in a cell or tissue, the greater the chance for affectation of disorder. Implications: Early stages of diabetes may be asymptomatic, and improvement in methodologies to identify individuals at high risk is important so prevention strategies can be targeted to susceptible individuals to slow or obviate the onset of disease and to minimize complications. Conclusions: Diabetes is a heterogeneous disorder, and accurate definition of phenotypes in the setting of non-syndromic and syndromic forms, development of powerful statistical methodologies, use of next-generation sequencing applications to interrogate the genome, incorporation of epigenetic mechanisms in statistical modeling and accurate curation of gene variants, will help us to realize application of genomic medicine and to inform diabetes care. Full article

Background: Advanced paternal age is increasingly encountered in assisted reproduction as parenthood is deferred. The clinical question is whether paternal age from about 40 to 45 years and older affects embryo development or outcomes, and to what extent any effect relates to the sperm epigenome. Methods: This narrative review synthesized PubMed-indexed evidence on sperm aging biology, including DNA methylation, chromatin packaging and nucleosome retention, small non-coding RNAs, telomere dynamics, DNA fragmentation, and oxidative and mitochondrial stress, and their potential clinical impact on assisted reproduction outcomes. Results: Maternal age remains the principal determinant of embryo aneuploidy. After multivariable adjustment, independent paternal-age effects on fertilization, blastocyst formation, and preimplantation genetic testing for aneuploidy are small or not detected. At very advanced paternal ages near or above 50 years, some studies report higher miscarriage and lower live birth, without a consistent change in early embryo morphology. Aging in men is linked to higher DNA fragmentation and oxidative and mitochondrial signatures, together with reproducible sperm-epigenome changes, including age-linked DNA methylation, altered histone retention, and small-RNA shifts. These molecular findings support modest intergenerational influences on early development, while stable transgenerational inheritance in humans is not supported. Conclusions: Advanced paternal age should be regarded as a risk modifier rather than a primary driver of preimplantation failure. Counseling should emphasize realistic effect sizes and the predominance of maternal age. Laboratory workflows should minimize oxidative stress. Selective DNA-fragmentation testing may be appropriate in recurrent ART failure or recurrent loss. Sperm-epigenome assays remain investigational and should undergo prospective, standardized validation before use in routine care. Full article

Familial cancers are caused by inherited mutations in specific genes that regulate cell growth, division, and repair. Approximately 5–10% of all cancer cases have a hereditary component, where germline mutations in certain genes increase an individual’s susceptibility to developing cancer. Two major categories of genes are involved in cancer development: tumour suppressor genes and oncogenes. Both play critical roles in regulating normal cell behaviour, and when mutated, they can contribute to uncontrolled cell proliferation and tumour formation. In addition to genetic mutations, epigenetic alterations also play a significant role in familial cancer. Epigenetics refers to changes in gene expression due to DNA methylation, histone modifications, and the dysregulation of non-coding RNAs without alter the underlying DNA sequence. Familial cancer syndromes follow various inheritance patterns, including autosomal dominant, autosomal recessive, X-linked, and mitochondrial inheritance, each with distinct characteristics. Identifying genetic mutations associated with familial cancers is a cornerstone of genetic counselling, which helps individuals and families navigate the complex intersection of genetics, cancer risk, and prevention. Early identification of mutations enables personalized strategies for risk reduction, early detection, and, when applicable, targeted treatment options, ultimately improving patient outcomes. Full article