Mitochondrial DNA copy number and risk of papillary thyroid carcinoma.

BACKGROUND: Mitochondrial DNA (mtDNA) copy number is associated with tumor activity and carcinogenesis. This study was undertaken to investigate mtDNA copy number in papillary thyroid cancer (PTC) tissues and to evaluate the risk of PTC development. The clinicopathological features of patients and mtDNA copy number were correlated. The value of mtDNA copy number was evaluated as a biomarker for PTC. METHOD: DNA was extracted from 105 PTC tissues and 67 control thyroid tissues, and mtDNA copy number mtDNA oxidative damage were determined using qPCR techniques. RESULTS: Overall, the relative mtDNA copy number was significantly higher in PTC patients (p < 0.001). The risk of developing PTC increased significantly across the tertiles of mtDNA copy number (p trend < 0.001). The higher the mtDNA copy number tertile, the greater the risk of developing PTC. Patients with follicular variants had an odds ratio of 2.09 (95% CI: 1.78-2.44) compared to those with classical variants (p < 0.001). The level of mtDNA oxidative damage in PTC was significantly elevated compared to controls (p < 0.001). The ROC analysis of mtDNA copy number indicated an area under the curve (AUC) of 77.7% (95% CI: 0.71 to 0.85, p < 0.001) for the ability of mtDNA copy number z-scores in differentiate between PTC and controls. CONCLUSION: Our results indicated that the augmentation of mtDNA content plays a significant role during the initiation of thyroid cancer, and it might represent a potential biomarker for predicting the risk of PTC.

Relative Telomere length in cervical exfoliated cells among women with high- risk human papillomavirus.

INTRODUCTION: This study investigates and compares the relative telomere length (RTL) outcome of high-risk (hr) human papillomavirus (HPV)-infected normal, low-grade squamous intraepithelial lesion (LSIL), and high-grade squamous intraepithelial lesion (HSIL) cervical samples to HPV-free normal cervical samples. METHODS: This study used archived cervical samples and obtained cytology and histology data. HPV genotyping was conducted using Sanger sequencing and RTL was performed using real-time quantitative polymerase chain reaction. RESULTS: This study investigated 287 cervical samples, including 100 normal and hr-HPV-negative samples from the control group, 44 normal and hr-HPV-infected samples, and 143 SIL and hr-HPV-infected samples. The RTL in hr-HPV-infected samples, including the SIL and normal sample groups, were significantly longer than that in the control group. RTL in HSIL (5.13 ± 3.22) and LSIL (2.86 ± 2.81) were significantly different (P < 0.001). The RTL of cervical intraepithelial neoplasia (CIN1) lesion (3.53 ± 2.53) differed significantly (P < 0.001) when compared to CIN2 and CIN3 lesions combined. The risk of developing cervical cancer was associated with RTL and was decreased with RTL. CONCLUSION: This study revealed the strong potential of the RTL test in identifying women at risk of developing cervical cancer.

Altered mitochondrial DNA copy number in cervical exfoliated cells among high­risk HPV­positive and HPV­negative women.

The majority of cervical cancer cases are due to human papillomavirus (HPV) infection. However, certain cases of cervical cancer are not caused by HPV. Recent studies have shown a link between altered mitochondrial DNA (mtDNA) copy number, an indicative measure of mitochondrial dysfunction, and cervical cancer in women who test positive for HPV. However, the role of the mtDNA copy number in HPV-negative cervical cancer has remained elusive. In the present study, the mtDNA copy number was determined using quantitative PCR as the ratio between mtDNA and nuclear DNA in 287 ThinPrep cervical samples, including 143 cases with cervical abnormalities and 144 control subjects with high-risk (hr)-HPV positive or HPV-negative status. In an overall analysis of cases categorized based on the cytology diagnosis into squamous cervical carcinoma/high-grade squamous intraepithelial lesions (SCC/HSIL), low-grade squamous intraepithelial lesions (LSIL) and normal controls, the mtDNA copy number was significantly higher in all cases compared to the controls and a higher mtDNA copy number was observed in SCC/HSIL compared to LSIL cases. In the stratification analyses based on hr-HPV positive and HPV-negative status, an increased mtDNA copy number was observed in the cases compared with the controls regardless of their HPV status (P<0.05). When cases with cervical abnormalities were categorized based on histological diagnosis into cervical intraepithelial neoplasia (CIN)2/CIN3 and CIN1, an overall analysis indicated an increased mtDNA copy number in CIN2/CIN3 compared to CIN1 (P=0.01). Stratification analyses of these cases based on HPV status revealed a higher mtDNA copy number in CIN2/CIN3 compared to CIN1 regardless of HPV infection (P<0.05). These results showed that an elevated mtDNA copy number in subjects with cervical abnormalities was not influenced by the HPV status and suggested the possibility of its role in the progression of cervical cancer. The increased mtDNA copy number may be an adaptive response mechanism to compensate for mtDNA oxidative stress and energy deficiency, possibly induced by HPV infection and other environmental exposures.

Comprehensive analysis of mitochondrial DNA variants, mitochondrial DNA copy number and oxidative damage in psoriatic arthritis.

Growing evidence suggests that abnormalities in mitochondrial DNA (mtDNA) are involved in the pathogenesis of various inflammatory and immuno-mediated diseases. The present study analysed the entire mitochondrial genome by next-generation sequencing (NGS) in 23 patients with psoriatic arthritis (PsA) and 20 healthy controls to identify PsA-related variants. Changes in mtDNA copy number (mtDNAcn) were also evaluated by quantitative polymerase chain reaction (qPCR) and mtDNA oxidative damage was measured using an 8-hydroxy-2'-deoxyguanosine assay. NGS analysis revealed a total of 435 variants including 187 in patients with PsA only and 122 in controls only. Additionally, 126 common variants were found, of which 2 variants differed significantly in their frequencies among patients and controls (P<0.05), and may be associated with susceptibility to PsA. A total of 33 missense variants in mtDNA-encoded genes for complexes I, III, IV and V were identified only in patients with PsA. Of them, 25 variants were predicted to be deleterious by affecting the functions and structures of encoded proteins, and 13 variants were predicted to affect protein's stability. mtDNAcn analysis revealed decreased mtDNA content in patients with PsA compared with controls (P=0.0001) but the decrease in mtDNAcn was not correlated with patients' age or inflammatory biomarkers (P>0.05). Moreover, a higher level of oxidative damage was observed in patients with PsA compared with controls (P=0.03). The results of the present comprehensive analysis of mtDNA in PsA revealed that certain mtDNA variants may be implicated in the predisposition/pathogenesis of PsA, highlighting the importance of NGS in the identification of mtDNA variants in PsA. The current results also demonstrated that decreased mtDNAcn in PsA may be a consequence of increased oxidative stress. These data provide valuable insights into the contribution of mtDNA defects to the pathogenesis of PsA. Additional studies in larger cohorts are needed to elucidate the role of mtDNA defects in PsA.

Mitochondrial DNA copy number in autism spectrum disorder and attention deficit hyperactivity disorder: a systematic review and meta-analysis.

Background: Several reports suggest that altered mitochondrial DNA copy number (mtDNA-cn), a common biomarker for aberrant mitochondrial function, is implicated in autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), but the results are still elusive. Methods: A meta-analysis was performed to summarize the current indication and to provide a more precise assessment of the mtDNA-cn in ASD and ADHD. A search in the MEDLINE-PubMed, Scopus, and EMBASE databases was done to identify related studies up to the end of February 2023. The meta-analysis was conducted according to recommendations of the Cochrane Handbook of Systematic Reviews. Results: Fourteen studies involving 666 cases with ASD and ADHD and 585 controls were collected and judged relevant for the systematic review and meta-analysis. The pooled results by a random effects meta-analysis was reported as a geometric mean of the estimated average response ratio and 95% confidence interval. Overall analysis of studies reported differences in mtDNA-cn in blood samples (k = 10) and non-blood samples (brain tissues and oral samples; k = 4) suggested significantly higher mtDNA-cn in patients compared to controls (p = 0.0275). Sub-analysis by stratifying studies based on tissue type, showed no significant increase in mtDNA-cn in blood samples among patients and controls (p = 0.284). Conversely, higher mtDNA-cn was observed in non-blood samples in patients than in controls (p = 0.0122). Further stratified analysis based on blood-cell compositions as potential confounds showed no significant difference in mtDNA-cn in peripheral blood samples of patients comparted to controls (p = 0.074). In addition, stratified analysis of aged-matched ASD and ADHD patients and controls revealed no significant difference in mtDNA-cn in blood samples between patients and controls (p = 0.214), whereas a significant increase in mtDNA-cn was observed in non-blood samples between patients and controls (p < 0.001). Finally, when the mtDNA-cn was analyzed in blood samples of aged-matched patients with ASD (peripheral blood, leukocytes, and PBMCs) or ADHD (peripheral blood), no significant difference in mtDNA-cn was observed between ASD patients and controls (p = 0.385), while a significant increase in mtDNA-cn was found between ADHD patients and controls (p = 0.033). Conclusion: In this first meta-analysis of the evaluation of mtDNA-cn in ASD/ADHD, our results show elevated mtDNA-cn in ASD and ADHD, further emphasizing the implication of mitochondrial dysfunction in neurodevelopmental disorders. However, our results indicate that the mtDNA-cn in blood is not reflected in other tissues in ASD/ADHD, and the true relationship between blood-derived mtDNA-cn and ASD/ADHD remains to be defined in future studies. The importance of blood-cell compositions as confounders of blood-based mtDNA-cn measurement and the advantages of salivary mtDNA-cn should be considered in future studies. Moreover, the potential of mtDNA-cn as a biomarker for mitochondrial malfunction in neurodevelopmental disorders deserves further investigations.

Mitochondrial DNA haplogroup analysis in Saudi Arab patients with multiple sclerosis.

Previous studies have suggested that mitochondrial DNA (mtDNA) variants are associated with multiple sclerosis (MS), a complex neurodegenerative immune-mediated disease of the central nervous system. Since mtDNA is maternally inherited without recombination, specific mtDNA variants defining genetic background are associated with the susceptibility to human diseases. To assess the contribution of mtDNA haplogroups to the predisposition of MS in an Arab population, we analysed sequencing data of mitochondrial genomes from 47 native Saudi Arab individuals including 23 patients with relapsing-remitting MS (RRMS) and 24 healthy controls. All patients and controls could be classified into ten haplogroups. The European-specific haplogroup U was more prevalent in patients than in the controls (26.1% vs. 4.2%), whereas haplogroup T was only present in patients and haplogroups HV and N were only found in controls. Haplogroup U was significantly association with increased risk of MS (odds ratio = 6.26, p<0.05), although the association did not maintain significance after adjustment for multiple comparisons. Haplotype U was more prevalent in patients with younger age of onset (p = 0.006), but there was no relationship between haplotype U and disease severity, disease duration or EDSS and age-matched carriers and non-carriers of haplogroup U (p>0.05). Definition site of haplogroup U include the variant m.12308A>G in MT-TL2 gene which was found to affect highly conserved position within the variable arm of tRNALeu(CUN) and thus may impact mitochondrial protein synthesis, and two other variants namely m.11467A>G in MT-ND4 gene and m.12372G>A in MT-ND5 gene which were previously linked with mitochondrial function. Despite the small number of subjects, which may limit the statistical power of the study, our results showed for the first time a possible contribution of haplogroup U to the predisposition to MS in an Arab population. These findings warrant further validation in a large cohort to distinguish a genuine effect specific to MS from a chance finding due to small sampling.

Leukocyte mitochondrial DNA copy number is a potential non-invasive biomarker for psoriasis.

Abnormalities in the mitochondria have been linked to psoriasis, a chronic immune-mediated inflammatory skin disease. The mitochondrial DNA (mtDNA) is present in thousands of copies per cell and altered mtDNA copy number (mtDNA-CN), a common indicator of mitochondrial function, has been proposed as a biomarker for several diseases including autoimmune diseases. In this case-control study, we investigated whether the mtDNA-CN is related to psoriasis, correlates with the disease duration and severity, and can serve as a disease biomarker. Relative mtDNA-CN as compared with nuclear DNA was measured by a quantitative real-time polymerase chain reaction in peripheral blood buffy coat samples from 56 patients with psoriasis and 44 healthy controls. The receiver operating characteristic (ROC) curve analysis was performed to evaluate the value of mtDNA-CN as a biomarker. We found that the mtDNA-CN was significantly decreased in patients with psoriasis compared to healthy controls (93.6±5.3 vs. 205±71; P = 0.04). Sub-group analyses with stratification of patients based on disease duration under or over 10 years and disease severity indicated that the mtDNA-CN was significantly lower in patients with longer disease duration (74±4.3 in disease duration >10 years vs. 79±8.3 in disease duration <10 years, P = 0.009), and higher disease severity (72±4.3 in moderate-to-severe index vs. 88.3 ± 6 in mild index, P = 0.017). Moreover, the mtDNA-CN was negatively correlated with the disease duration and disease severity (r = -0.36, P = 0.006; r = -0.41, P = 0.003 respectively). The ROC analysis of mtDNA-CN showed an area under the curve (AUC) of 0.84 (95% confidence interval: 0.69-0.98; P = 0.002) for differentiating patients from healthy controls. Our study suggests that low mtDNA-CN may be an early abnormality in psoriasis and associates with the disease progression. Our study also suggests that mtDNA-CN may be a novel blood-based biomarker for the early detection of psoriasis.

Next-generation sequencing of the whole mitochondrial genome identifies functionally deleterious mutations in patients with multiple sclerosis.

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system with genetics and environmental determinants. Studies focused on the neurogenetics of MS showed that mitochondrial DNA (mtDNA) mutations that can ultimately lead to mitochondrial dysfunction, alter brain energy metabolism and cause neurodegeneration. We analyzed the whole mitochondrial genome using next-generation sequencing (NGS) from 47 Saudi individuals, 23 patients with relapsing-remitting MS and 24 healthy controls to identify mtDNA disease-related mutations/variants. A large number of variants were detected in the D-loop and coding genes of mtDNA. While distinct unique variants were only present in patients or only occur in controls, a number of common variants were shared among the two groups. The prevalence of some common variants differed significantly between patients and controls, thus could be implicated in susceptibility to MS. Of the unique variants only present in the patients, 34 were missense mutations, located in different mtDNA-encoded genes. Seven of these mutations were not previously reported in MS, and predicted to be deleterious with considerable impacts on the functions and structures of encoded-proteins and may play a role in the pathogenesis of MS. These include two heteroplasmic mutations namely 10237T>C in MT-ND3 gene and 15884G>C in MT-CYB gene; and three homoplasmic mutations namely 9288A>G in MT-CO3 gene, 14484T>C in MT-ND6 gene, 15431G>A in MT-CYB gene, 8490T>C in MT-ATP8 gene and 5437C>T in MT-ND2 gene. Notably some patients harboured multiple mutations while other patients carried the same mutations. This study is the first to sequence the entire mitochondrial genome in MS patients in an Arab population. Our results expanded the mutational spectrum of mtDNA variants in MS and highlighted the efficiency of NGS in population-specific mtDNA variant discovery. Further investigations in a larger cohort are warranted to confirm the role of mtDNA MS.

Next-generation sequencing of the whole mitochondrial genome identifies novel and common variants in patients with psoriasis, type 2 diabetes mellitus and psoriasis with comorbid type 2 diabetes mellitus.

Recent studies have shown the role of mitochondrial DNA (mtDNA) variants in the pathogenesis of both psoriasis (Ps) and type 2 diabetes (T2D) amongst different ethnicities. However, no studies have investigated the mtDNA variants present in patients with Ps, T2D, and both Ps and T2D (Ps-T2D) in the Arab population. The entire mitochondrial genomes of Kuwaiti subjects with Ps, T2D, Ps-T2D and healthy controls were sequenced using Ion Torrent next-generation sequencing. A total of 36 novel mutations and 51 previously reported mutations were identified in the patient groups that were absent in the controls. Amongst the novel mutations, eight were non-synonymous and exhibited amino acid changes. Of these, two missense mutations (G5262A and A12397G) in the ND genes were detected in the Ps group and a C15735T missense mutation in the CYB gene was detected in Ps-T2D. Other known sequence variations were seen more frequently in all or certain patient groups compared with the controls (P<0.05). Additionally, the A8701G missense mutation in the ATPase 6 gene missense mutation was also observed in a higher frequency in the Ps group compared with the control. The present study is the first to perform a complete mitochondrial genome sequence analysis of Kuwaiti subjects with Ps, T2D and Ps-T2D, and both novel and known mtDNA variants were discovered. The patient-specific novel non-synonymous mutations may be co-responsible in the determination of these diseases. The higher frequency of certain mtDNA variants in the patients compared with the controls may suggest a role in predisposing patients to these diseases. Further functional analyses are required to reveal the role of the identified mutations in these disease conditions.

Mitochondrial Haplogroup Reveals the Genetic Basis of Diabetes Mellitus Type 2 Comorbidity in Psoriasis.

OBJECTIVE: Published data show a clear link between psoriasis (Ps) and the increasing prevalence of comorbid conditions, such as diabetes mellitus type 2 (DM2). The role of the mitochondrial genomic haplogroup in the potential coexistence of Ps and DM2 comorbidity is the subject of this study. MATERIAL AND METHODS: Ninety-eight Kuwaiti individuals were recruited in 4 cohorts (20 healthy controls, 15 with DM2, 34 with Ps, and 29 with Ps and diabetes mellitus). An Ion Torrent S5XL was used to sequence mitochondrial DNA (mtDNA). χ2 test was used to assess differences in the distribution of each haplogroup between cases and controls (p < 0.05). The Bonferroni correction was applied (p < 0.004). The mtDNA haplogroups were analyzed by HaploGrep. RESULTS: Haplogroups R0, U, J, T, N, L3, M, H, X, HV, R, and K were detected in the studied population. Haplogroup M had a high risk for Ps (odds ratio (OR) 4.0, p = 0.003). Haplogroup R0 and J had decreased the risk of DM2 (OR 0.28, p = 0.007). CONCLUSION: Our results indicated that mtDNA haplogroups have a potential contribution to the pathogenesis of Ps and DM2 comorbidity. We show for the first time that the comorbidity of diabetes in Ps may be related to mitochondrial dysfunction.