Succinate-CoA ligase (SUCL) is a heterodimer enzyme composed of Suclg1 α-subunit and a substrate-specific Sucla2 or Suclg2 β-subunit yielding ATP or GTP, respectively. In humans, the deficiency of this enzyme leads to encephalomyopathy with or without methylmalonyl aciduria, in addition to resulting in mitochondrial DNA depletion. We generated mice lacking either one Sucla2 or Suclg2 allele. Sucla2 heterozygote mice exhibited tissue- and age-dependent decreases in Sucla2 expression associated with decreases in ATP-forming activity, but rebound increases in cardiac Suclg2 expression and GTP-forming activity. Bioenergetic parameters including substrate-level phosphorylation (SLP) were not different between wild-type and Sucla2 heterozygote mice unless a submaximal pharmacological inhibition of SUCL was concomitantly present. mtDNA contents were moderately decreased, but blood carnitine esters were significantly elevated. Suclg2 heterozygote mice exhibited decreases in Suclg2 expression but no rebound increases in Sucla2 expression or changes in bioenergetic parameters. Surprisingly, deletion of one Suclg2 allele in Sucla2 heterozygote mice still led to a rebound but protracted increase in Suclg2 expression, yielding double heterozygote mice with no alterations in GTP-forming activity or SLP, but more pronounced changes in mtDNA content and blood carnitine esters, and an increase in succinate dehydrogenase activity. We conclude that a partial reduction in Sucla2 elicits rebound increases in Suclg2 expression, which is sufficiently dominant to overcome even a concomitant deletion of one Suclg2 allele, pleiotropically affecting metabolic pathways associated with SUCL. These results as well as the availability of the transgenic mouse colonies will be of value in understanding SUCL deficiency.

Genome-Wide Non-Invasive Prenatal Testing (GW-NIPT) can provide positive results not only for common autosomal aneuploidies but also for rare autosomal trisomies (RATs) and structural chromosomal abnormalities (StrCAs). Due to their rarity, there is currently insufficient information on positive predictive value PPV of RAT and StrCA-positive cases in the literature. In this study, the screening accuracy and pregnancy outcomes of cases positive for rare chromosomal abnormalities were examined based on publications in which GW-NIPT testing was performed. True positive cases were determined using two different methodologies. One was a confirmed methodology, where only cases validated by genetic testing were considered true positives with a definite diagnosis, and the other was an extended methodology, where, in addition to cases confirmed by genetic testing, intrauterine fetal death and termination of pregnancy due to an abnormality confirmed by ultrasound examination were also considered true positives, where no diagnosis had been made but the fetus was probably affected. Seventeen studies were analyzed, with a total GW-NIPT population of 740,076. Of these, 1,738 were RAT positive. Using the confirmed method, we found the highest rates of true positives in T16, followed by T22, and T2, using the extended method, the highest rate of true positives in T15, T16 and T22. This is the first meta-analysis to determine the frequency of rare chromosomal abnormalities, test-positive rates, and the PPV of each chromosomal abnormality with high precision. Our results could aid pre- and post-test genetic counselling and help patients and clinicians in their decision-making.

There is no literature available about the growth differentiation factor-15 (GDF-15) biomarker in combination with mitochondrial DNA (mtDNA) deletions in insulin resistance (IR), and polycystic ovary syndrome (PCOS); however, it would be useful to achieve optimal metabolic status and improve pregnancy success. In this study, the role of GDF-15 and mtDNA deletions as biomarkers in the pathogenesis of IR and PCOS was investigated. In our study, 81 female patients who were treated for IR and/or PCOS and 41 healthy controls were included. GDF-15 levels in patients showed a marked increase compared to controls. Elevated GDF-15 levels were found in 12 patients; all of them had a BMI > 25 kg/m², which is associated with reactive hyperinsulinemia. The presence of mitochondrial dysfunction was mainly observed in the IR-only subgroup. The increase in plasma levels of GDF-15 and the prevalence of mtDNA deletions is directly proportional to body mass index. The more marked metabolic abnormalities required more intensive drug therapy with a parallel increase in plasma GDF-15 levels. Elevated levels of GDF-15 and the presence of mitochondrial DNA deletions may be a consequence of carbohydrate metabolism disorders in patients and thus a predictor of the process of accelerated aging.

Genome-wide noninvasive prenatal testing has introduced new challenges in clinical interpretation, for example, due to discrepancies between noninvasive prenatal testing and confirmatory invasive results caused by confined placental mosaicism. These discordant cases often involve rare autosomal trisomies, frequently attributed to placental mosaicism. Complex, multichromosomal false-positive genome-wide noninvasive prenatal testing results are usually not due to placental mosaicism but rather to maternal malignancy, for example. This study aimed to assess chromosome-specific associations with pregnancy complications and uniparental disomy in false-positive rare autosomal trisomies and the prevalence of maternal malignancies in complex, multichromosomal genome-wide noninvasive prenatal testing results. A systematic search of 5 databases-MEDLINE (via PubMed), Embase, Cochrane, Scopus, and Web of Science-was conducted on August 28, 2025. Cohort studies using massively parallel sequencing were included. The study population was pregnant women who had undergone genome-wide noninvasive prenatal testing and had a known pregnancy outcome. Data extraction followed a standardized protocol, risk of bias was assessed using the Quality in Prognostic Studies tool, and statistical analyses were performed in R (v4.1.2) using a random-effects model. Sixteen eligible studies encompassing 681,633 pregnancies were included. Rare autosomal trisomy-positive results occurred in only 0.2% of cases and 80% were false positives. Notably, ∼35% of these were associated with adverse pregnancy outcomes, predominantly involving chromosomes 2, 4, 11, 16, and 22. Uniparental disomy was most commonly associated with trisomies 15 and 16. In cases with complex genome-wide noninvasive prenatal testing findings, 40% were ultimately diagnosed with maternal malignancy, primarily breast cancer and lymphoma. Discordant genome-wide noninvasive prenatal testing results are associated with an increased risk of placenta-mediated complications. Among rare autosomal trisomies, trisomy 16 and, to a lesser extent, trisomy 4 consistently showed the highest risks. These results imply that chromosome-specific risk stratification could inform prenatal counseling and follow-up. Additionally, complex, multichromosomal genome-wide noninvasive prenatal testing results were occasionally associated with maternal malignancies. This emphasizes the importance of considering both maternal and fetal contributions when interpreting such results.

Mitochondrial dysfunction contributes to female reproductive endocrine disorders and is frequently associated with multisystem symptoms. Insulin resistance (IR) is a common metabolic disorder strongly linked to polycystic ovary syndrome (PCOS), while premature ovarian insufficiency (POI) also impairs fertility. Mitochondrial DNA (mtDNA) deletions and the stress-responsive cytokine growth differentiation factor 15 (GDF-15) have recently emerged as complementary biomarkers of mitochondrial impairment. In this retrospective observational study, we examined reproductive hormones, plasma GDF-15, mtDNA deletions, and clinical symptoms in insulin-resistant women, including those with PCOS or POI. Eighty-one patients were divided into three subgroups: IR-only (n = 49), IR-PCOS (n = 19), and IR-POI (n = 13). IR was defined based on elevated insulin levels during oral glucose tolerance testing (>10 mU/L at 0 min, >50 mU/L at 60 min, >30 mU/L at 120 min) according to national gynecological endocrinology guidelines, acknowledging that IR is not universally accepted as a distinct clinical entity. POI was defined as reduced ovarian reserve before age 40 with anti-Müllerian hormone (AMH) <1.0 ng/mL. Clinical symptoms were assessed using a questionnaire, medical record, and physical examination. MtDNA deletions were detected by long-range PCR, and GDF-15 was measured by ELISA. Free thyroxine (T4) emerged as an independent predictor of GDF-15, suggesting that thyroid function modulates mitochondrial stress signaling in insulin-resistant women. MtDNA deletions and/or elevated GDF-15 correlated with endocrine, gastrointestinal, and neuropsychiatric symptoms, and reduced AMH/FSH ratios indicated impaired ovarian function. Cross-sectional analysis further revealed lower AMH and AMH/FSH ratios in older women with mtDNA deletions, consistent with a trend toward accelerated reproductive aging. Overall, these findings support the role of GDF-15 and mtDNA deletions as complementary biomarkers of mitonuclear stress, with potential relevance for both systemic and reproductive health.