Length Heteroplasmy Research Articles

Sequencing the hypervariable regions of human mitochondrial DNA using massively parallel sequencing: Enhanced data acquisition for DNA samples encountered in forensic testing.

Mitochondrial DNA testing is a useful tool in the analysis of forensic biological evidence. In cases where nuclear DNA is damaged or limited in quantity, the higher copy number of mitochondrial genomes available in a sample can provide information about the source of a sample. Currently, Sanger-type sequencing (STS) is the primary method to develop mitochondrial DNA profiles. This method is laborious and time consuming. Massively parallel sequencing (MPS) can increase the amount of information obtained from mitochondrial DNA samples while improving turnaround time by decreasing the numbers of manipulations and more so by exploiting high throughput analyses to obtain interpretable results. In this study 18 buccal swabs, three different tissue samples from five individuals, and four bones samples from casework were sequenced at hypervariable regions I and II using STS and MPS. Sample enrichment for STS and MPS was PCR-based. Library preparation for MPS was performed using Nextera® XT DNA Sample Preparation Kit and sequencing was performed on the MiSeq™ (Illumina, Inc.). MPS yielded full concordance of base calls with STS results, and the newer methodology was able to resolve length heteroplasmy in homopolymeric regions. This study demonstrates short amplicon MPS of mitochondrial DNA is feasible, can provide information not possible with STS, and lays the groundwork for development of a whole genome sequencing strategy for degraded samples.

Full mtGenome reference data: development and characterization of 588 forensic-quality haplotypes representing three U.S. populations.

Though investigations into the use of massively parallel sequencing technologies for the generation of complete mitochondrial genome (mtGenome) profiles from difficult forensic specimens are well underway in multiple laboratories, the high quality population reference data necessary to support full mtGenome typing in the forensic context are lacking. To address this deficiency, we have developed 588 complete mtGenome haplotypes, spanning three U.S. population groups (African American, Caucasian and Hispanic) from anonymized, randomly-sampled specimens. Data production utilized an 8-amplicon, 135 sequencing reaction Sanger-based protocol, performed in semi-automated fashion on robotic instrumentation. Data review followed an intensive multi-step strategy that included a minimum of three independent reviews of the raw data at two laboratories; repeat screenings of all insertions, deletions, heteroplasmies, transversions and any additional private mutations; and a check for phylogenetic feasibility. For all three populations, nearly complete resolution of the haplotypes was achieved with full mtGenome sequences: 90.3-98.8% of haplotypes were unique per population, an improvement of 7.7-29.2% over control region sequencing alone, and zero haplotypes overlapped between populations. Inferred maternal biogeographic ancestry frequencies for each population and heteroplasmy rates in the control region were generally consistent with published datasets. In the coding region, nearly 90% of individuals exhibited length heteroplasmy in the 12418-12425 adenine homopolymer; and despite a relatively high rate of point heteroplasmy (23.8% of individuals across the entire molecule), coding region point heteroplasmies shared by more than one individual were notably absent, and transversion-type heteroplasmies were extremely rare. The ratio of nonsynonymous to synonymous changes among point heteroplasmies in the protein-coding genes (1:1.3) and average pathogenicity scores in comparison to data reported for complete substitutions in previous studies seem to provide some additional support for the role of purifying selection in the evolution of the human mtGenome. Overall, these thoroughly vetted full mtGenome population reference data can serve as a standard against which the quality and features of future mtGenome datasets (especially those developed via massively parallel sequencing) may be evaluated, and will provide a solid foundation for the generation of complete mtGenome haplotype frequency estimates for forensic applications.

Primer effect in the detection of mtDNA heteroplasmy: insights from horse Cytochrome b gene

Heteroplasmy, the presence of bi-allelic mtDNA types within an individual, has been previously detected in the D-loop region and Cytochrome b gene (Cytb) of mitochondrial DNA using PCR-RFLP. However, heteroplasmy was absent in thousands of equine mtDNA sequences deposited in GenBank. To address whether heteroplasmy widely exists in mitochondria of Chinese indigenous horses, we generated the data set of the target sites in Cytb region with Sanger sequencing and PCR-RFLP method as well. In this study, 23 heteroplasmic individuals were detected in 430 Chinese local horses. Both site and length heteroplasmy were identified in horse Cytb, especially in Xinihe and Ujumqin breeds. Our data provide evidence that the forward and reverse primers seem to produce a similar approximation to the proportion of mutation base call. However, locations of primers affected the proper detection of mtDNA heteroplasmy. The data obtained in this study highlight the importance of the primers in the accurate detection of heteroplasmy.

Comparison of base composition analysis and Sanger sequencing of mitochondrial DNA for four U.S. population groups

A set of 711 samples from four U.S. population groups was analyzed using a novel mass spectrometry based method for mitochondrial DNA (mtDNA) base composition profiling. Comparison of the mass spectrometry results with Sanger sequencing derived data yielded a concordance rate of 99.97%. Length heteroplasmy was identified in 46% of samples and point heteroplasmy was observed in 6.6% of samples in the combined mass spectral and Sanger data set. Using discrimination capacity as a metric, Sanger sequencing of the full control region had the highest discriminatory power, followed by the mass spectrometry base composition method, which was more discriminating than Sanger sequencing of just the hypervariable regions. This trend is in agreement with the number of nucleotides covered by each of the three assays.

Mass spectrometric base composition profiling: Implications for forensic mtDNA databasing

In forensic genetics mitochondrial DNA (mtDNA) is usually analyzed by direct Sanger-type sequencing (STS). This method is known to be laborious and sometimes prone to human error. Alternative methods have been proposed that lead to faster results. Among these are methods that involve mass-spectrometry resulting in base composition profiles that are, by definition, less informative than the full nucleotide sequence. Here, we applied a highly automated electrospray ionization mass spectrometry (ESI-MS) system (PLEX-ID) to an mtDNA population study to compare its performance with respect to throughput and concordance to STS. We found that the loss of information power was relatively low compared to the gain in speed and analytical standardization. The detection of point and length heteroplasmy turned out to be roughly comparable between the technologies with some individual differences related to the processes. We confirm that ESI-MS provides a valuable platform for analyzing mtDNA variation that can also be applied in the forensic context.

Lack of Structural Variation but Extensive Length Polymorphisms and Heteroplasmic Length Variations in the Mitochondrial DNA Control Region of Highly Inbred Crested Ibis, Nipponia nippon

The animal mitochondrial DNA (mtDNA) length polymorphism and heteroplasmy are accepted to be universal. Here we report the lack of structural variation but the presence of length polymorphism as well as heteroplasmy in mtDNA control region of an endangered avian species – the Crested Ibis (Nipponia nippon). The complete control region was directly sequenced while the distribution pattern and inheritance of the length variations were examined using both direct sequencing and genotyping of the PCR fragments from captive birds with pedigrees, wild birds and a historical specimen. Our results demonstrated that there was no structural variation in the control region, however, different numbers of short tandem repeats with an identical motif of CA3CA2CA3 at the 3′-end of the control region determined the length polymorphisms among and heteroplasmy within individual birds. There were one to three predominant fragments in every bird; nevertheless multiple minor fragments coexist in all birds. These extremely high polymorphisms were suggested to have derived from the ‘replication slippage’ of a perfect microsatellite evolution following the step-wise mutational model. The patterns of heteroplasmy were found to be shifted between generations and among siblings but rather stable between blood and feather samples. This study provides the first evidence of a very extensive mtDNA length polymorphism and heteroplasmy in the highly inbred Crested Ibis which carries an mtDNA genome lack of structural genetic diversity. The analysis of pedigreed samples also sheds light on the transmission of mtDNA length heteroplasmy in birds following the genetic bottleneck theory. Further research focusing on the generation and transmission of particular mtDNA heteroplasmy patterns in single germ line of Crested Ibis is encouraged by this study.

Heteroplasmy and length variation in the tRNApro-Dloop regions of three sturgeon species (A. stellatus, A. gueldenstaedtii and H. huso) from the Turkish coast of the Black Sea

Objective: To determine tandem repeat polymorphism and heteroplasmy in three sturgeon species (A. stellatus, A. gueldenstaedtii and H. huso) from the Turkish coast of Black Sea. Methods: tRNApro and D-loop segment of mtDNA from three sturgeon species were amplified via PCR and sequenced. For each species, homoplasmic individuals with different product lengths, repeat motifs and regions were determined and the repeat numbers and frequencies were calculated. The variation in mtDNA size present in the overall sample of sturgeon from Turkish waters was apportioned into hierarchical components. Also, the statistical approach described by other researchers was used for the calculation of inter- species and intra-species genetic variation. Results: The results showed that all three species reveal 2-6 copies of different mtDNA length variants attributable to varying copy numbers of an 82-84bp repeat sequences. A total of 9.9% of the sturgeons were heteroplasmic, bearing three to five repeat variants. The highest number of observed repeat units rate was 45.8% in 3 repeats morph in A. gueldenstaedtii. The mean genetic diversity within individuals (Kb) was higher in A. gueldenstaedtii and A. stellatus than in H. huso (0.625, 0.620, and 0.500, respectively). Conclusion: The repeat region, responsible for length variations and heteroplasmy, is located near the end of the D-loop and control region separated by only a few nucleotides from the tRNApro gene.

STR and mitochondrial DNA SNP typing of a bone marrow transplant recipient after death in a fire

Personal identification of a house fire victim is described. About 5 years prior to death, the victim had been underwent bone marrow transplantation (BMT) with a graft from an unrelated donor as treatment for acute myelogenous leukemia. Clinically, the victim had been in remission at the time of death. Typing of STRs and sequencing of mitochondrial DNA (mtDNA) were performed using blood from the heart as well as several soft (psoas major muscle, uterine muscle and mucous membrane of the urinary bladder) and hard (costal cartilage and nail) tissues. STR genotypes and amelogenin from each of the tissue samples were successfully typed, and the parentage was identified. The blood STR types demonstrated no relationship with those from other tissues. None of the blood STR loci showed extra peaks arising from those of the recipient. Therefore, the blood stem cells were assumed to have been altered to those of the donor. The genotypes of mtDNA control regions were also examined. The electropherogram of hypervariable region II (nucleotide positions 29-408) obtained from the blood revealed a similar length heteroplasmy, suggesting microchimerism of the blood. Sequence analysis of mtDNA might be applicable as a more sensitive method for determination of chimerisms after BMT.

Repetitive sequences in Eurasian lynx (Lynx lynx L.) mitochondrial DNA control region

Mitochondrial DNA (mtDNA) control region (CR) of numerous species is known to include up to five different repetitive sequences (RS1–RS5) that are found at various locations, involving motifs of different length and extensive length heteroplasmy. Two repetitive sequences (RS2 and RS3) on opposite sides of mtDNA central conserved region have been described in domestic cat (Felis catus) and some other felid species. However, the presence of repetitive sequence RS3 has not been detected in Eurasian lynx (Lynx lynx) yet. We analyzed mtDNA CR of 35 Eurasian lynx (L. lynx L.) samples to characterize repetitive sequences and to compare them with those found in other felid species. We confirmed the presence of 80 base pairs (bp) repetitive sequence (RS2) at the 5′ end of the Eurasian lynx mtDNA CR L strand and for the first time we described RS3 repetitive sequence at its 3′ end, consisting of an array of tandem repeats five to ten bp long. We found that felid species share similar RS3 repetitive pattern and fundamental repeat motif TACAC.

The complete mitochondrial genome analysis of the tiger (Panthera tigris)

The complete mitochondrial genomes of five tiger samples from three subspecies (P. t. sumatrae, P. t. altica, and P. t. tigris) were successfully obtained by using 26 specifically designed Panthera-specific primer sets. The genome organization and gene arrangement of the five tiger samples were similar to each other; however polymorphic tandem repeat sequences were observed in the control region (CR). This led to a difference in the genome lengths obtained from these five samples with an average size of 16,994bp for the five tiger mitochondrial genomes. The nucleotide base composition was on average as follows: A, 31.8%; T, 27.0%; C, 26.6%; G, 14.6% and exhibited compositional asymmetry. Most of tiger mitochondrial genome characteristics are similar to those of other common vertebrate species; however, some distinctive features were observed in the CR. First, the repetitive sequence 2 (RS 2) contained two repeat units of 80bp and the first 15bp of what would be the third repeat motif. The repetitive sequence 3 (RS 3) contained 47-50 repeat motifs of a shorter 8bp (ACGTAYAC)(n). Second, length heteroplasmy polycystosine (poly-C) stretches was observed at the end of the HV I locus in all tiger samples.

The occurrence of mtDNA heteroplasmy in multiple cetacean species

In population genetics and phylogenetic studies, mitochondrial DNA (mtDNA) is commonly used for examining differences both between and within groups of individuals. For these studies, correct interpretation of every nucleotide position is crucial but can be complicated by the presence of ambiguous bases resulting from heteroplasmy. Particularly for non-model taxa, the presence of heteroplasmy in mtDNA is rarely reported, therefore, it is unclear how commonly it occurs and how it can affect phylogenetic relationships among taxa and the overall understanding of evolutionary processes. We examined the occurrence of both site and length heteroplasmy within the mtDNA of ten marine mammal species, for most of which mtDNA heteroplasmy has never been reported. After sequencing a portion of the mtDNA control region for 5,062 individuals, we found heteroplasmy in at least 2% of individuals from seven species, including Stenella frontalis where 58.9% were heteroplasmic. We verified the presence of true heteroplasmy, ruling out artifacts from amplification and sequencing methods and the presence of nuclear copies of mitochondrial genes. We found no evidence that mtDNA heteroplasmy influenced phylogenetic relationships, however, its occurrence does have the potential to increase the genetic diversity for all species in which it is found. This study stresses the importance of both detecting and reporting the occurrence of heteroplasmy in wild populations in order to enhance the knowledge of both the introduction and the persistence of mutant mitochondrial haplotypes in the evolutionary process.

Evaluating sequence-derived mtDNA length heteroplasmy by amplicon size analysis

Length heteroplasmy (LH) in mitochondrial (mt)DNA is usually observed in homopolymeric tracts and manifest as mixture of various length variants. The generally used difference-coded annotation to report mtDNA haplotypes does not express the degree of LH variation present in a sample, even more so, it is sometimes difficult to establish which length variants are present and clearly distinguishable from background noise. It has therefore become routine practice for some researchers to call the dominant type, the “major molecule”, which represents the LH variant that is most abundant in a DNA extract. In the majority of cases a clear single dominant variant can be identified. However, in some samples this interpretation is difficult, i.e. when (almost) equally quantitative LH variants are present or when multiple sequencing primers result in the presentation of different dominant types. To better understand those cases we designed amplicon sizing assays for the five most relevant LH regions in the mtDNA control region (around ntps 16,189, 310, 460, 573, and the AC-repeat between 514 and 524) to determine the ratio of the LH variants by fluorescence based amplicon sizing assays. For difficult LH constellations derived by Sanger sequencing (with Big Dye terminators) these assays mostly gave clear and unambiguous results. In the vast majority of cases we found agreement between the results of the sequence and amplicon analyses and propose this alternative method in difficult cases.

Alterations of Length Heteroplasmy in Mitochondrial DNA Under Various Amplification Conditions*

There are several areas within mitochondrial DNA that show length heteroplasmy. If the heteroplasmy pattern is unique and consistent for each person, it may be used to support an interpretation of exclusion in identity testing. We investigated whether the length heteroplasmy pattern would be consistent under different amplification conditions. We also determined whether various amplification parameters would affect the homopolymeric cytosine stretches (C-stretch) in HV1. Monoclonal samples tended to be heteroplasmic after amplification. After several repetitions, C-stretch patterns of all samples were inconsistent even under the same amplification conditions. Increased PCR cycles and high template concentrations resulted in a more frequent heteroplasmic tendency. These amplification parameters seem to have little effect if samples are not long enough in C-stretch or total length of the segment from nt 16180 to nt 16193. It is suggested that the pattern of length heteroplasmy cannot be used as an additional polymorphic marker.

Heteroplasmy in Hair: Study of Mitochondrial DNA Third Hypervariable Region in Hair and Blood Samples*†

Mitochondrial DNA (mtDNA) analysis has proved useful for forensic identification especially in cases where nuclear DNA is not available, such as with hair evidence. Heteroplasmy, the presence of more than one type of mtDNA in one individual, is a common situation often reported in the first and second mtDNA hypervariable regions (HV1/HV2), particularly in hair samples. However, there is no data about heteroplasmy frequency in the third mtDNA hypervariable region (HV3). To investigate possible heteroplasmy hotspots, HV3 from hair and blood samples of 100 individuals were sequenced and compared. No point heteroplasmy was observed, but length heteroplasmy was, both in C-stretch and CA repeat. To observe which CA "alleles" were present in each tissue, PCR products were cloned and re-sequenced. However, no variation among CA alleles was observed. Regarding forensic practice, we conclude that point heteroplasmy in HV3 is not as frequent as in the HV1/HV2.

Erratum to: Evaluating length heteroplasmy in the human mitochondrial DNA control region

we will quantify the two mutation rates in Table 5 as separate sections 1 and 2 has incorrectly been published as we will quantify the two mutation rates in Table 5 as separate sections Introduction and Subjects and methods. The sentence Assuming in the high-radiation area a mutation rate of 1/600 transmissions for loss of four cytosines, 1/ 600 for loss of three cytosines, and 4/600 for a loss of two cytosines (Table 5), the probability to observe the child's sequence, given the putative mother is the true mother, is approximately 1/600=0.17% has been incorrectly published as Assuming in the high-radiation area a mutation rate of one out of 1/600 transmissions for loss of four cytosines, one out of 1/600 for loss of three cytosines, and four out of 4/600 for a loss of two cytosines (Table 5), the probability to observe the child's sequence, given the putative mother is the true mother, is approximately 1/600=0.17%.

Characterization of Retinal and Blood Mitochondrial DNA from Age-Related Macular Degeneration Patients

To determine mitochondrial (mt)DNA variants in AMD and age-matched normal retinas. Total DNA was isolated from retinas (AMD, n = 13; age-matched normal, n = 13), choroid (AMD, n = 3), and blood (AMD, n = 138; normal, n = 133). Long-extension-polymerase chain reaction amplified the full-length ( approximately 16.2 kb) mtDNA genome. Retinal mtDNA was sequenced for nucleotide variants and length heteroplasmy. Pyrosequencing was performed on heteroplasmic mtDNA. PCR amplification and enzyme digestions were used to analyze for nucleotide changes. Retinal mtDNA had a greater number of rearrangements and deletions than did blood mtDNA in normal samples (9.3 +/- 1.78 vs. 3 +/- 1.18, P = 0.019), and AMD samples (14.33 +/- 1.96 vs. 5.2 +/- 0.80, P = 0.0031. Five (55%) of 9 AMD patients had unreported SNPs, and 2 (16.6%) of 12 of the normal group did. The mtDNA coding region had 20 SNPs that produced amino acid changes. The noncoding MT-Dloop region had nucleotide heteroplasmy and length heteroplasmy. There were more SNPs per person in the AMD population than in the older (P = 0.003) and younger (P = 0.05) normal subjects. The C12557T (T-I) in the MT-ND5 gene was present in two AMD subjects (2/138) but was absent in the normal (0/133). Common mutations for Leber's hereditary optic neuropathy (LHON: G11778A; T14484C; and G3460A) were not present in AMD samples. AMD subjects have high levels of large mtDNA deletions/rearrangements in the retinas, unreported and amino acid-changing SNPs in the coding genome, and a greater number of SNPs per person in the noncoding MT-Dloop region. These mtDNA variants could diminish energy production efficiency, alter the mtDNA copy numbers and/or impact transcription in AMD retinas.

Mitochondrial DNA sequence analysis of a native Bolivian population

Mitochondrial DNA analysis is very useful for the interpretation of the history of human migration and to estimate the frequency of a haplotype in the forensic context. From a human settlement perspective, La Paz area is greatly interesting since the first planned city of the region is located there. Samples from 110 individuals from La Paz were studied analysing the polymorphisms in the D-loop, hypervariable region I (HVI) and hypervariable region II (HVII) in order to verify the genetic diversity. The aim of this study was to start the creation of a population database in order to obtain the genetic interpopulation variability and classify haplotypes into characteristic haplogroups of South America. A total of 97 different haplotypes were identified, 90 being unique, expressed by 122 polymorphic nucleotide positions. Nucleotide and sequence diversity were estimated to be 0.015 ± 0.0075 and 0.996, respectively. Haplogroup distribution in the samples was 57.27% B4, 19.09% C1, 10.00% A2, 3.64% D1, 2.73% D4h3, 1.82% H, and 0.91% for each of the haplogroups A4, B4c1a, CZ, D4J, M7a and M8/N9b. The rate of length heteroplasmy was 36.36% in HVI and 52.73% in HVII. Phylogenetic analysis reveals proximity to the Korean, Chilean aboriginal, Japanese and Australian populations. The estimated genetic variability of the studied population was high, suggesting an early settlement.

Bovine mtDNA D-loop haplotypes exceed mutations in number despite reduced recombination: an effective alternative for identity control

Mitochondrial (mt) DNA D-loop heterogeneity, haplotype distribution and possible sub-population structures within the relevant populations are important for DNA-based traceability. To gain insight into this distribution, we compared 1515 Bos taurus mtDNA D-loop sequences available from GenBank to 219 sequences that we sequenced de novo. A pronounced ambiguous trace typical of C-track length heteroplasmy was encountered in 5% of the samples, which were excluded from the analysis. Previously undescribed mutations and haplotypes were observed in 6% and 63% of the sequences, respectively. B. taurus haplotypes divided into the taurus, indicus and grunniens types and 302 variable sites formed the 858 taurus haplotypes detected. Fifty-five sites displayed a complex level of variation. As each level represents an independent mutation event, a total of 399 mutations were traced, which could potentially explain independent formation of less than half (47%) of the haplotypes encountered: most haplotypes were derived from different combinations of these mutations. We suggest that a mutational hotspot may explain these results and discuss the usefulness of mtDNA for identity and maternity assurance.

Evaluating length heteroplasmy in the human mitochondrial DNA control region

We present allelic data for three known and one new C-tract in the human mitochondrial DNA (mtDNA) control region, and we measure intergenerational mutation rates at such C-tracts. In detail, in a sample of 1,172 mtDNA sequences, we demonstrate the existence of an instability threshold of eight consecutive cytosines, at and above which the phenomenon of length heteroplasmy arises. To determine mutation rates, we draw on mtDNA sequences in up to four generations of 248 pedigrees for families living in high or low-radiation environmental conditions. The high-radiation sample gives the most conservative (fastest) mutation rate likely to be encountered in any forensic context. We find that the C-tract mutation rate is up to 6% per generation, and we observe an excess of cytosine gains over losses. Case studies and guidelines for evaluating mtDNA heteroplasmy are provided.

Profound Length Heteroplasmic Alterations in Mitochondrial DNA Control Region From Primary AML Cells: Implication of Impaired Mitochondrial Replication and Demonstration of ‘vicious cycle' Hypothesis.

Abstract 3116Poster Board III-53Mitochondrial DNA (mtDNA) control region (displacement (D)-loop including HV1 and HV2) is a non-coding region of 1124 bp (nucleotide positions, np 16 024–576), which acts as a promoter for both the heavy and light strands of mtDNA, and contains essential transcription and replication elements (Blood 2004;103:4466-77). Importantly, mutations in the D-loop regulatory region might change mtDNA replication rate by modifying the binding affinity of significant trans-activating factors (Eur J Cancer 2004;40:2519-24). Thus, length heteroplasmic alterations of mtDNA control region may be related with mitochondrial dysfunction resulting in ‘vicious cycle' (Mol Med Today 2000;6:425-32). In an attempt to investigate profiling of mtDNA length heteroplasmic alterations in primary AML cells, we carried out a quantitative size-based PCR product separation by capillary electrophoresis (ABI 3130XL Genetic Analyzer and ABI Prism Genotyper version 3.1) using six targets (np 303-315 poly C, np 16184-16193 poly C, np 514-511 CA repeats, np 3566-3572 poly C, np 12385-12391 poly C and np 12418-12426 poly A). Length heteroplasmy was further confirmed by cloning and sequencing. Quantitative analysis of mtDNA molecules was performed using the QuantiTect SYBR Green PCR kit (Qiagen) and Rotor-Gene 3000 (Corbett Research). Forty-eight AML bone marrow samples were collected after receiving Institutional Review Board approval and informed consent. There were profound alterations of mtGI in 303 poly C, 16184 poly C and 514 CA repeats. The length heteroplasmy pattern of 303 poly C tract in the HV2 region disclosed mixture of 7C, 8C, 9C and 10C mtDNA types. In the HV2 region, length heteroplasmy in poly-C tract at np 303 - 309 exhibited 5 variant peak patterns: 7CT6C+8CT6C (50.0%), 8CT6C+9CT6C (14.0%), 8CT6C+ 9CT6C+ 10CT6C (10.4%), 9CT6C+10CT6C+11CT6C (8.3%) 9CT6C + 10CT6C + 11CT6C+12CT6C (2.1%). The length heteroplasmy pattern of 514-523 CA repeats in the HV2 region exhibited 2 variant peak patterns: CACACACACA (56.3%) and CACACACA (43.7%). In the HV1 region, length heteroplasmy in the poly-C tract at np 16184 - 16193 exhibited 9 variant peak patterns: 5CT4C+5CT3C (31.0%), 6CT4C+6CT3C (2.1%), 9C+10C+11C+12C (16.7%), 9C+10C+11C (2.1%), T4CT4C+5CT3C (4.2%), 9C+10C+11C+12C+13C (2.1%), 3CTC4C+5CT3C (2.1%), 10C+11C+12C+13C (4.2%), 8C+9C+10+11C (2.1%). Primary AML cells revealed decreased enzyme activity in respiratory chain complex I, II and III. AML cells had about a two-fold decrease in mtDNA copy number compared with normal blood mononuclear cells. Current study demonstrates that profound length heteroplasmic alterations in mtDNA control region of primary AML cells may lead to impairment of mitochondrial biogenesis (reduction of mtDNA copy number) and derangement of mitochondrial ATP synthesis. During this perturbation, mitochondria in primary AML cells might produce a large amount of reactive oxygen species, which causes the vicious cycle observed in chronic inflammatory diseases and cancers as well. DisclosuresNo relevant conflicts of interest to declare.