Mitochondrial DNA and TFAM gene variation in early-onset myocardial infarction: Evidence for an association to haplogroup H

Mitochondrial Heteroplasmy as a Marker for Premature Coronary Artery Disease: Analysis of the Poly-C Tract of the Control Region Sequence

Mitochondrial DNA (mtDNA) differs from the nuclear genome in many aspects: a maternal inheritance pattern; being more prone to acquire somatic de novo mutations, accumulative with age; and the possible coexistence of different mtDNA alleles (heteroplasmy). Mitochondria are key cellular organelles responsible for energy production and involved in complex mechanisms, including atherosclerosis. In this scenario, we aimed to evaluate mtDNA variants that could be associated with premature cardiovascular disease. We evaluated 188 consecutive patients presenting with premature myocardial infarction with ST elevation (STEMI) confirmed by coronary angiogram. mtDNA polymorphisms and clinical data were evaluated and compared with 271 individuals from the same population (control group). Tobacco consumption (80.85% vs. 21.21%, p < 0.01) and dyslipidemia (38.83% vs. 28.41%, p = 0.02) were significantly more frequent among STEMI patients. Moreover, C16223T mtDNA mutation and poly-C heteroplasmy were significantly more frequent among premature STEMI male patients than in controls. The OR associated C16223T mtDNA with the increased presence of cardiovascular risk factors. Our data suggest that mtDNA 16223T and heteroplasmy may be associated with unstable premature atherosclerosis disease in men. Moreover, the presence of cardiovascular risk factors (CVRFs) was associated with C16223T mtDNA, with a cumulative effect. Protective mitochondrial pathways are potential therapeutic targets. Preventing exposure to the damaging mechanisms associated with CVRFs is of utmost importance.

Mitochondria-related TFAM gene variants and their effects on patients with cervical cancer

Cervical cancer is the fourth most common type of cancer in women worldwide, with high incidence and mortality rates, particularly in developing countries. There are human papillomavirus vaccines and cytological screening programs available; however, there are no molecular markers that would aid the prognosis of the course of the disease or prediction of the outcomes of the patients. The aim of the present study was to investigate the associations between single nucleotide polymorphisms (SNPs) of the mitochondrial transcription factor A (TFAM) gene (rs11006132, rs11006129, rs1937, rs16912174, rs16912202 and rs3900887), and the clinical parameters and tumor phenotype of patients with cervical cancer. DNA isolated from patients with cervical cancer (n=172) was used for genotyping using Real-Time PCR using TaqMan probes. It was revealed that the TFAM rs3900887 TT and AT genotypes were associated with a lower risk of developing larger tumors. The results showed an association between the rs3900887 SNP and tumor phenotype, indicating TFAM rs3900887 as a potential biomarker for tumor size in cervical cancer.

Pilot Screening of Cell-Free mtDNA in NIPT: Quality Control, Variant Calling, and Haplogroup Determination

Clinical tests based on whole-genome sequencing are generally focused on a single task approach, testing one or several parameters, although whole-genome sequencing (WGS) provides us with large data sets that can be used for many supportive analyses. In spite of low genome coverage, data of WGS-based non-invasive prenatal testing (NIPT) contain fully sequenced mitochondrial DNA (mtDNA). This mtDNA can be used for variant calling, ancestry analysis, population studies and other approaches that extend NIPT functionality. In this study, we analyse mtDNA pool from 645 cell-free DNA (cfDNA) samples of pregnant women from different regions of Russia, explore the effects of transportation and storing conditions on mtDNA content, analyse effects, frequency and location of mitochondrial variants called from samples and perform haplogroup analysis, revealing the most common mitochondrial superclades. We have shown that, despite the relatively low sequencing depth of unamplified mtDNA from cfDNA samples, the mtDNA analysis in these samples is still an informative instrument suitable for research and screening purposes.

The APOB polymorphism rs1801701 A/G (p.R3638Q) is an independent risk factor for early-onset coronary artery disease: Data from a Spanish cohort

BACKGROUND AND AIMS

Apoliprotein B (ApoB) has been associated with hypercholesterolemia and ischemic coronary disease. This study was aimed to determine the effect of two APOB gene variants in the risk of developing early-onset coronary artery disease (EO-CAD) in a Spanish population. The association of these polymorphisms with hypercholesterolemia was also analysed.

METHODS AND RESULTS

The study involved a total of 889 healthy population controls (397 male) and 790 EO-CAD cases (636 male; EO-CAD was defined as male <60 years and women <65 years). All the patients had at least one vessel with angiography documented atherosclerotic lesion. Patients and controls were genotyped for the APOB variants rs1801701 A/G (p.R3638Q) and rs1367117 C/T (p.T98I). Allele and genotype frequencies were compared between the groups (patients vs. controls, hyper-vs. normo-cholesterolemia) by logistic regression. The rs1801701 was significantly associated with EO-CAD in male (OR = 1.44, 95%CI = 1.05-1.99) and female (OR = 2.22, 95%CI = 1.58-3.14). This SNP was significantly associated with hypercholesterolemia in female, with a trend in male. The association with EO-CAD was independent of hypercholesterolemia (multiple logistic regression).

CONCLUSION

A common APOB polymorphism (rs1801701) was an independent risk factor for EO-CAD in our population. The risk-effect was more significant in female than in male.

The impact of mitochondria-related POLG and TFAM variants on breast cancer pathomorphological characteristics and patient outcomes

PURPOSE

Breast cancer is the most frequent female cancer, leading to relapse with distant metastasis of approximately one-third of patients. Cancer is usually considered a genetic disease involving mutations in nuclear DNA. However, genes, coding for mitochondrial proteins or regulatory molecules, are rarely under consideration. This study aimed to analyse 10 single nucleotide variants in POLG and TFAM genes and assess their association with tumour phenotype and disease outcome.

MATERIALS AND METHODS

A total of 234 breast cancer patients were included in this study. Variations were determined with Real-Time PCR using TaqMan^® probes.

RESULTS

We found that patients with POLG rs2307441 TT and CT genotypes had a lower probability for vascular invasion than those with CC genotype (p = 0.001). Patients with POLG rs2072267 AG genotype were predisposed for progression compared with GG genotype (p = 0.015). TFAM rs3900887 TT genotype was associated with a higher probability for positive oestrogen receptors (p = 0.003) and lymphatic invasion (p = 0.001) in comparison to AA genotype, patients with TT (p = 0.000) were more likely to have positive lymph nodes.

CONCLUSIONS

Our data suggest that variations in POLG and TFAM genes are important determinacies of tumour phenotype and disease outcome in breast cancer patients.

Gene variants in the NF-KB pathway (NFKB1, NFKBIA, NFKBIZ) and risk for early-onset coronary artery disease

The nuclear-factor kappa-beta (NF-KB) is a driver of inflammation, and plays an important role in the pathogenesis of atherosclerosis and coronary artery disease (CAD). Early-onset CAD is defined as a coronary ischaemic episode at an age ≤55 years, and in our population was strongly associated with male sex and smoking. Our aim was to determine whether common variants in three NF-KB genes were associated with early-onset CAD. We studied 609 patients with early-onset CAD and 423 healthy controls, all male. Allele and genotype frequencies for the NFKB1 rs28362491 (-94 delATTG) and NFKBIA rs8904 were not significantly different between the two groups. For the NFKBIZ rs3217713, the deletion allele was significantly more frequent in the patients than in controls (0.27 vs. 0.22; p = 0.004). Deletion-carriers were more frequent in the patients (p < 0.001), with an OR = 1.48 (95%CI = 1.15-1.90). We performed a multiple logistic regression (linear generalized model) with smoking, hypercholesterolemia, type 2 diabetes, hypertension, and the rs3217713 deletion carriers remained significantly associated with early-onset CAD (p = 0.01). In our population, the NFKBIZ variant was an independent risk factor for developing early-onset CAD.

Involvement of mitochondrial haplogroups in myocardial infarction and stroke: A case-control study in Castile and Leon (Spain) population

There are strong evidences that common mitochondrial DNA (mtDNA) haplogroups may influence the pathogenesis of cardiovascular diseases (CVDs). In this matched case-control study, we investigate the association between mtDNA haplogroups and two CVDs, myocardial infarction (MI) and stroke, and classical cardiovascular risk factors. Data obtained show that haplogroup H constitute a susceptibility risk factor for MI (p=0.001; OR=2.379, 95% CI [1.440-3.990]). Otherwise, our data also suggest a beneficial role of haplogroup J against hypertension (p=0.019; OR=0.348, 95% CI [0.144-0.840]). These results may provide some guidance for predicting the genetic risk of these diseases in different human populations through the differences in energy efficiency between haplogroups.

Polymorphisms in the TFAM and PGC1-α genes and their association with polycystic ovary syndrome among South Indian women

We investigated the link between polymorphisms in genes involved in mitochondrial biogenesis, mitochondrial transcription factor A (TFAM) and Peroxisome proliferator activated receptor gamma coactivator-1 alpha (PGC-1α) and further studied the role of these genes on the pathophysiology of polycystic ovary syndrome (PCOS). This case-control study was carried out in 118 PCOS cases and 110 controls. In the present study we genotyped three polymorphisms of PGC1-α gene (rs8192678-Gly482Ser, rs13131226 and rs2970856) and polymorphism of TFAM gene (rs1937-+35G/C) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. In addition, to better understand genetic contributions to the pathophysiology of PCOS, mtDNA copy number (MCN) was quantified using a qRT-PCR assay in the subjects. The results revealed that the distribution of genotypes and allele frequency of the PGC-1α Gly482Ser polymorphism in PCOS patients was statistically significant from those of the control group respectively (OR-2.488; 95% CI-1.0673 to 5.7998; P=0.047), (OR-1.6091; 95% CI-1.0955 to 2.3634; P=0.015) indicating that the presence of 'A' allele might confer risk to PCOS. Patients with the 'AA' genotype showed significantly lower levels of MCN compared with patients with other genotypes. In addition, patients carrying CT genotype of PGC1-α rs2970856 demonstrated significantly higher levels of LH (P=0.030) than TT and CC genotypes. In conclusion, our study indicates that carriers of the PGC-1α rs8192678 'Ser' allele have increased risk of developing PCOS.

Pandora's Box: mitochondrial defects in ischaemic heart disease and stroke

Ischaemic heart disease and stroke are vascular events with serious health consequences worldwide. Recent genetic and epigenetic techniques have revealed many genetic determinants of these vascular events and simplified the approaches to research focused on ischaemic heart disease and stroke. The pathogenetic mechanisms of ischaemic heart disease and stroke are complex, with mitochondrial involvement (partially or entirely) recently gaining substantial support. Not only can mitochondrial reactive oxygen species give rise to ischaemic heart disease and stroke by production of oxidised low-density lipoprotein and induction of apoptosis, but the impact on pericytes contributes directly to the pathogenesis. Over the past two decades, publications implicate the causative role of nuclear genes in the development of ischaemic heart disease and stroke, in contrast to the potential role of mitochondrial DNA (mtDNA) in the pathophysiology of the disorders, which is much less understood, although recent studies do demonstrate that the involvement of mitochondria and mtDNA in the development of ischaemic heart disease and stroke is likely to be larger than originally thought, with the novel discovery of links among mitochondria, mtDNA and vascular events. Here we explore the molecular events and mtDNA alterations in relation to the role of mitochondria in ischaemic heart disease and stroke.

Low Cytochrome Oxidase 1 Links Mitochondrial Dysfunction to Atherosclerosis in Mice and Pigs

Background

Cytochrome oxidase IV complex regulates energy production in mitochondria. Therefore, we determined the relation of COX genes with atherosclerosis in mice and pigs.

Methods and results

First, we compared atherosclerosis in the aortic arch of age-matched (24 weeks) C57BL/6J control (n = 10), LDL-receptor deficient (n = 8), leptin-deficient ob/ob (n = 10), and double knock-out (lacking LDL-receptor and leptin) mice (n = 12). Low aortic mitochondria-encoded cytochrome oxidase 1 in obese diabetic double knock-out mice was associated with a larger plaque area and higher propensity of M1 macrophages and oxidized LDL. Caloric restriction increased mitochondria-encoded cytochrome oxidase 1 and reduced plaque area and oxidized LDL. This was associated with a reduction of titer of anti-oxidized LDL antibodies, a proxy of systemic oxidative stress. Low of mitochondria-encoded cytochrome oxidase 1 was related to low expression of peroxisome proliferative activated receptors α, δ, and γ and of peroxisome proliferative activated receptor, gamma, co-activator 1 alpha reflecting mitochondrial dysfunction. Caloric restriction increased them. To investigate if there was a diabetic/obesity requirement for mitochondria-encoded cytochrome oxidase 1 to be down-regulated, we then studied atherosclerosis in LAD of hypercholesterolemic pigs (n = 37). Pigs at the end of the study were divided in three groups based on increasing LAD plaque complexity according to Stary (Stary I: n = 12; Stary II: n = 13; Stary III: n = 12). Low mitochondria-encoded cytochrome oxidase 1 in isolated plaque macrophages was associated with more complex coronary plaques and oxidized LDL. Nucleus-encoded cytochrome oxidase 4I1 and cytochrome oxidase 10 did not correlate with plaque complexity and oxidative stress. In mice and pigs, MT-COI was inversely related to insulin resistance.

Conclusions

Low MT-COI is related to mitochondrial dysfunction, oxidative stress and atherosclerosis and plaque complexity.

Health and genetic ancestry testing: time to bridge the gap

BACKGROUND

It is becoming increasingly difficult to keep information about genetic ancestry separate from information about health, and consumers of genetic ancestry tests are becoming more aware of the potential health risks associated with particular ancestral lineages. Because some of the proposed associations have received little attention from oversight agencies and professional genetic associations, scientific developments are currently outpacing governance regimes for consumer genetic testing.

MAIN TEXT

We highlight the recent and unremarked upon emergence of biomedical studies linking markers of genetic ancestry to disease risks, and show that this body of scientific research is becoming part of public discourse connecting ancestry and health. For instance, data on genome-wide ancestry informative markers are being used to assess health risks, and we document over 100 biomedical research articles that propose associations between mitochondrial DNA and Y chromosome markers of genetic ancestry and a wide variety of disease risks. Taking as an example an association between coronary heart disease and British men belonging to Y chromosome haplogroup I, we show how this science was translated into mainstream and online media, and how it circulates among consumers of genetic tests for ancestry. We find wide variations in how the science is interpreted, which suggests the potential for confusion or misunderstanding.

CONCLUSION

We recommend that stakeholders involved in creating and using estimates of genetic ancestry reconsider their policies for communicating with each other and with the public about the health implications of ancestry information.

Effects of mitochondrial haplogroup N9a on type 2 diabetes mellitus and its associated complications

A case-control study was conducted with the aim of identifying the predominant haplogroups associated with type 2 diabetes mellitus (T2DM) and its complications. In addition, the role of N9a in T2DM risk and complications was analyzed. Sequencing of the entire mitochondrial DNA was conducted in 235 patients and 244 controls in cohort 1, and six haplogroups (F, B4, D4, D5, M8a and N9a) associated with T2DM were classified. The frequency of N9a was further determined in cohort 2 (440 patients and 244 controls) and examined in two combined cohorts, including 675 patients with T2DM and 649 non-diabetic controls. Multivariate logistic regression analysis and association analysis were performed to investigate the association between genotypes, T2DM and diabetic nephropathy. M8a [P=0.011; odds ratio (OR), 3.49; 95% confidence interval (CI), 1.26-9.69] and haplogroup N9a (P=0.023; OR, 2.60; 95% CI, 1.11-6.05) were associated with an increased risk of T2DM. The frequency of N9a was higher in T2DM patients compared with that in the controls (6.2% vs. 4.3%) and associated with a mild risk (P=0.10; OR, 1.51; 95% CI, 0.92-2.49). N9a was significantly associated with an increased risk of diabetic nephropathy (P=0.024; OR, 2.15; 95% CI, 1.11-4.19). Previous findings of N9a being protective against T2DM were not replicated in the present study, although this haplogroup was associated with an increased risk of diabetic nephropathy.

Mito-nuclear co-evolution: the positive and negative sides of functional ancient mutations

Most cell functions are carried out by interacting factors, thus underlying the functional importance of genetic interactions between genes, termed epistasis. Epistasis could be under strong selective pressures especially in conditions where the mutation rate of one of the interacting partners notably differs from the other. Accordingly, the order of magnitude higher mitochondrial DNA (mtDNA) mutation rate as compared to the nuclear DNA (nDNA) of all tested animals, should influence systems involving mitochondrial-nuclear (mito-nuclear) interactions. Such is the case of the energy producing oxidative phosphorylation (OXPHOS) and mitochondrial translational machineries which are comprised of factors encoded by both the mtDNA and the nDNA. Additionally, the mitochondrial RNA transcription and mtDNA replication systems are operated by nDNA-encoded proteins that bind mtDNA regulatory elements. As these systems are central to cell life there is strong selection toward mito-nuclear co-evolution to maintain their function. However, it is unclear whether (A) mito-nuclear co-evolution befalls only to retain mitochondrial functions during evolution or, also, (B) serves as an adaptive tool to adjust for the evolving energetic demands as species' complexity increases. As the first step to answer these questions we discuss evidence of both negative and adaptive (positive) selection acting on the mtDNA and nDNA-encoded genes and the effect of both types of selection on mito-nuclear interacting factors. Emphasis is given to the crucial role of recurrent ancient (nodal) mutations in such selective events. We apply this point-of-view to the three available types of mito-nuclear co-evolution: protein-protein (within the OXPHOS system), protein-RNA (mainly within the mitochondrial ribosome), and protein-DNA (at the mitochondrial replication and transcription machineries).

Mitochondrial DNA haplogroups and risk of new-onset diabetes among tacrolimus-treated renal transplanted patients

BACKGROUND AND AIMS

Tacrolimus (Tac) is an immunosuppressive drug widely used to avoid organ rejection. New-onset diabetes after transplantation (NODAT) is a major complication among transplanted patients who receive Tac. The increased risk for NODAT could be partly mediated by the effect of Tac on mitochondria from pancreatic beta-cells. Common and rare mitochondrial DNA variants have been linked to the risk of diabetes. Our aim was to determine whether mtDNA polymorphisms/haplogroups were associated with NODAT in Tac-treated kidney transplanted.

METHODS

Seven polymorphisms that define the common European haplogroups were determined in 115 NODAT and 197 no-NODAT patients.

RESULTS

Haplogroup H was significantly more frequent in the NODAT group (50% vs. 35%; p=0.01, OR=1.82). There was no difference between patients without and with (n=106) D2M prior to the transplant.

CONCLUSIONS

Mitochondrial haplogroup H was associated with the risk for NODAT among Tac-treated transplanted patients. The reported differences between the mtDNA variants could explain the increased NODAT-risk among H-patients.

Association between a MYH9 polymorphism (rs3752462) and renal function in the Spanish RENASTUR cohort

The MYH9 gene encodes a protein that is expressed in the kidney glomerular podocytes. MYH9 single nucleotide polymorphisms (SNPs) have been linked to the risk for chronic kidney disease (CKD) and end stage renal disease. Our aim was to determine whether MYH9 SNPs were associated with renal disease in Spanish Caucasians. The RENASTUR cohort consisted of 592 Spanish Caucasians, aged 55-85 years. They were genotyped for SNPs rs3752462 and rs4821480, which tagged haplotype E. The main values between individuals with a glomerular filtration rate (eGFR) <60 and ≥ 60 ml/min/1.73 m(2) were statistically compared. The next variables were significantly associated with the eGFR in the univariate analysis: age, gender, type 2 diabetes, total cholesterol, total LDL-cholesterol, and the MYH9 rs3752462 (TC+TT genotypes; p=0.003). This SNP remained significantly associated with the eGFR in the multivariate analysis. In conclusion, SNP rs3752462 was an independent predictor of reduced eGFR in the Spanish RENASTUR population. The genotyping of this MYH9 SNP could help to identify individuals at risk of developing CKD.

Hypervariable region polymorphism of mtDNA of recurrent oral ulceration in Chinese

Background

MtDNA haplogroups could have important implication for understanding of the relationship between the mutations of the mitochondrial genome and diseases. Distribution of a variety of diseases among these haplogroups showed that some of the mitochondrial haplogroups are predisposed to disease. To examine the susceptibility of mtDNA haplogroups to ROU, we sequenced the mtDNA HV1, HV2 and HV3 in Chinese ROU.

Methodology/Principal Findings

MtDNA haplogroups were analyzed in the 249 cases of ROU patients and the 237 cases of healthy controls respectively by means of primer extension analysis and DNA sequencing. Haplogroups G1 and H were found significantly more abundant in ROU patients than in healthy persons, while haplogroups D5 and R showed a trend toward a higher frequency in control as compared to those in patients. The distribution of C-stretch sequences polymorphism in mtDNA HV1, HV2 and HV3 regions was found in diversity.

Conclusions/Significance

For the first time, the relationship of mtDNA haplogroups and ROU in Chinese was investigated. Our results indicated that mtDNA haplogroups G1 and H might constitute a risk factor for ROU, which possibly increasing the susceptibility of ROU. Meanwhile, haplogroups D5 and R were indicated as protective factors for ROU. The polymorphisms of C-stretch sequences might being unstable and influence the mtDNA replication fidelity.

Mitochondrial haplogroups H and J: risk and protective factors for ischemic cardiomyopathy

Background

Since mitochondria are the principal source of reactive oxygen species (ROS), these organelles may play an important role in ischemic cardiomyopathy (IC) development. The mitochondrial genome may influence this disease. The aim of the present study was to test the relationship between IC development and the impact of single nucleotide polymorphisms (SNPs) in mitochondrial DNA (mtDNA) defining the mitochondrial haplogroups in a population study.

Methodology and principal findings

Ten major European haplogroups were identified by using the single base extension technique and by polymerase chain reaction-restriction fragment length polymorphism. Frequencies and Odds Ratios for the association between IC patients (n = 358) and healthy controls (n = 423) were calculated. No convincing associations between classical risk factors for ischemic cardiomyopathy development and haplogroups were found. However, compared to healthy controls, the prevalence of haplogroup H was significantly higher in IC patients (40.0% vs 50.0%, p-value  = 0.039) while the frequency of haplogroup J was significantly lower (11.1% vs 5.6%, p-value  = 0.048). The analysis of the SNPs characterizing the European mtDNA haplogroups showed that the m.7028C allele (40.0% vs 50.0%, p-value  = 0.005) and m.14766C allele (43.0% vs 54.2%, p-value  = 0.002) were overrepresented in IC patients, meanwhile the m.10398G allele (19.8% vs 13.1%, p-value  = 0.015) and m.4216C allele (22.2% vs 16.5%, p-value  = 0.044) were found as protective factors against IC.

Conclusions and significance

Our results showed that the haplogroups H and J were found as a risk and protective factors for ischemic cardiomyopathy development, respectively.

Mitochondrial diversity patterns and the Magdalenian resettlement of Europe: new insights from the edge of the Franco-Cantabrian refuge

Phylogeography of the mitochondrial lineages commonly found in Western Europe can be interpreted in the light of a postglacial resettlement of the continent. The center of this proposal lies in the Franco-Cantabrian glacial refuge, located in the northern Iberian Peninsula and Southwestern France. Recently, this interpretation has been confronted by the unexpected patterns of diversity found in some European haplogroups. To shed new lights on this issue, research on Iberian populations is crucial if events behind the actual genetics of the European continent are to be untangled. In this regard, the region of Asturias has not been extensively studied, despite its convoluted history with prolonged periods of isolation. As mitochondrial DNA is a kind of data that has been commonly used in human population genetics, we conducted a thorough regional study in which we collected buccal swabs from 429 individuals with confirmed Asturian ancestry. The joint analysis of these sequences with a large continent-wide database and previously published diversity patterns allowed us to discuss a new explanation for the population dynamics inside the Franco-Cantabrian area, based on range expansion theory. This approximation to previously contradictory findings has made them compatible with most proposals about the postglacial resettlement of Western Europe.

Common European mitochondrial haplogroups in the risk for psoriasis and psoriatic arthritis

Mitochondrial dysfunction could contribute to the pathogenesis of psoriasis (Ps) and Ps-arthritis (PsA). Several common mtDNA polymorphisms/haplogroups have been linked to differences in the production of reactive oxygen species and mitochondrial oxidative damage. To test the hypothesis of an association between mtDNA variants and Ps/PsA, we studied the single-nucleotide polymorphisms that define the common European haplogroups in a total of 325 patients and 300 controls from Spain. No allele/haplogroup was significantly associated with the risk for Ps. However, haplogroup J was significantly less frequent among patients with PsA, suggesting a protective effect in our population (p=0.04; odds ratio=0.39). We concluded that mtDNA may have a role in Ps and PsA.

Mitochondrial haplogroups associated with end-stage heart failure and coronary allograft vasculopathy in heart transplant patients

AIMS

Mitochondrial haplogroups are known to influence individual predisposition to a wide spectrum of metabolic and degenerative diseases, including ischaemic cardiovascular diseases. We have examined the influence of the mitochondrial DNA (mtDNA) background on the development of human end-stage heart failure (HF) in patients undergoing heart transplantation. The influence of mtDNA haplogroups on the incidence of transplant-related complications, mainly cardiac allograft vasculopathy (CAV), and on post-transplant survival was also studied.

METHODS AND RESULTS

The most common mitochondrial haplogroups in European populations were genotyped in 450 heart transplant recipients, 248 heart transplant donors, and 206 healthy controls. Mitochondrial haplogroups were determined by PCR amplification of short mtDNA fragments, followed by restriction fragment length polymorphism analysis. After adjustment for age and sex the frequency of haplogroup H was significantly higher in heart transplant recipients than in controls [OR: 1.86 (95% confidence intervals, CI: 1.27-2.74), P= 0.014], and in heart donors [OR: 1.47 (95% CI: 0.99-2.19), P= 0.032]. Likewise, haplogroup Uk was found significantly more frequently among CAV patients than in non-CAV heart allograft recipients [OR: 4.1 (95% CI: 1.51-11.42), P= 0.042]. Finally, heart donor haplogroups had no influence on the morbidity or mortality after heart transplantation.

CONCLUSIONS

Mitochondrial haplogroups behave like risk factors for the progress to end-stage HF in a Spanish cardiac transplant population. Mitochondrial DNA variants may have some influence on the appearance of cardiac transplant complications.