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Mitochondrial DNA sequence variation in single cells from leukemia patients.

ABSTRACT: A high frequency of mtDNA somatic mutation has been observed in many tumors as well as in aging tissues. In this study, we analyzed the mtDNA control region sequence variation in 3534 single normal cells and individual blasts from 18 patients with leukemia and 10 healthy donors, to address the mutation process in leukemic cells. We found significant differences in mtDNA sequence, as represented by the number of haplotypes and the mean number of cells with each nonaggregate haplotype in a population of cells, in patients compared to controls. Patients with similar clinical leukemia types, particularly acute myeloid leukemia (AML), did not show a uniform pattern of sequence variation in single blasts. Some patients at relapse presented a complex shift of major haplotypes in single cells. Four patients showed high frequencies of cells containing mutations 189, 260, 16150, and 16488, respectively, as a result of clonal expansion and could be considered as potential markers for their respective disease progression. To our knowledge, this is the first large-scale study of mtDNA variation in single malignant cells. Our results suggest that the somatic mutation process in leukemia is complex, leading to diverse levels of genetic alterations due to either intrinsic aspects of leukemia pathophysiology or chemotherapy effects.

SUBMITTER: Yao YG

PROVIDER: S-EPMC1785100 | biostudies-literature | 2007 Jan

REPOSITORIES: biostudies-literature

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Mitochondrial DNA sequence variation in single cells from leukemia patients.

Yao Yong-Gang YG Ogasawara Yoji Y Kajigaya Sachiko S Molldrem Jeffrey J JJ Falcão Roberto P RP Pintão Maria-Carolina MC McCoy J Philip JP Rizzatti Edgar Gil EG Young Neal S NS

Blood 20060831 2

A high frequency of mtDNA somatic mutation has been observed in many tumors as well as in aging tissues. In this study, we analyzed the mtDNA control region sequence variation in 3534 single normal cells and individual blasts from 18 patients with leukemia and 10 healthy donors, to address the mutation process in leukemic cells. We found significant differences in mtDNA sequence, as represented by the number of haplotypes and the mean number of cells with each nonaggregate haplotype in a populat ...[more]

PMID: 16946307

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Project description:The aim of the present study was to explore variations of the displacement (D)-loop region in patients with acute myeloid leukemia (AML) and their possible associations with AML pathogenesis. Blood or bone marrow samples from 216 patients with AML (158 AML patients in the first stage, and 58 more patients with AML-M3 for further verification), and 146 healthy controls were collected. Sanger sequencing was performed for the D-loop region ranging between nucleotide (nt)15811 and nt 775. With the exception of mitochondrial microsatellite instability (mtMSI) variations, a total of 2,630 variations in 232 loci were identified with similar variation rates/person in patients with AML and controls when compared with the revised Cambridge reference sequence (8.54±2.14 vs. 8.77±2.15; P=0.366). A positive association between AML and variation-T152C was identified, which occurred more frequently in patients with AML compared with in controls [26.6 vs. 17.1%; P=0.048; odds ratio (OR), 1.752; 95% confidence interval (CI), 1.004-3.058]. Furthermore, T152C was identified to be associated with promyelocytic leukemia-retinoic acid receptor α(PML-RARα) and French-American-British AML subtypes, with a tendency to occur in patients with AML-M3. The AML-M3 sample size was extended by 58 cases, and it was identified that the T152C variation rate was significantly higher in patients with AML-M3 compared with that of controls (41.0 vs. 17.1%; P<0.001; OR, 3.228; 95% CI, 1.714-6.079). However, no association was identified between the T152C variation and clinical characteristics, or chemotherapy response in patients with AML-M3. In addition, the mtMSIs, including D310, mt514-523 (CA)n and T16189C, demonstrated no association with AML risk. Together, the results of the present study suggest that the mitochondrial DNA D-loop region is high variable, and that T152C is associated with AML risk, particularly regarding the M3 subtype. T152C mayparticipate in AML pathogenesis and may be a diagnostic biomarker; however further studies with larger sample sizes are required in order to verify its value.

Project description:BACKGROUND: Leber hereditary optic neuropathy (LHON, MIM 535000) is one of the most common mitochondrial genetic disorders caused by three primary mtDNA mutations (m.3460G>A, m.11778G>A and m. 14484T>C). The clinical expression of LHON is affected by many additional factors, e.g. mtDNA background, nuclear genes, and environmental factors. Hitherto, there is no comprehensive study of Chinese LHON patients with m.14484T>C. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we analyzed the mtDNA sequence variations and haplogroup distribution pattern of the largest number of Chinese LHON patients with m.14484T>C to date. We first determined the complete mtDNA sequences in eleven LHON probands with m.14484T>C, to discern the potentially pathogenic mutations that co-segregate with m.14484T>C. We then dissected the matrilineal structure of 52 patients with m.14484T>C (including 14 from unrelated families and 38 sporadic cases) and compared it with the reported Han Chinese from general populations. Complete mtDNA sequencing showed that the eleven matrilines belonged to nine haplogroups including Y2, C4a, M8a, M10a1a, G1a1, G2a1, G2b2, D5a2a1, and D5c. We did not identify putatively pathogenic mutation that was co-segregated with m.14484T>C in these lineages based on the evolutionary analysis. Compared with the reported Han Chinese from general populations, the LHON patients with m.14484T>C had significantly higher frequency of haplogroups C, G, M10, and Y, but a lower frequency of haplogroup F. Intriguingly, we also observed a lower prevalence of F lineages in LHON subjects with m.11778G>A in our previous study, suggesting that this haplogroup may enact similar role during the onset of LHON in the presence of m.14484T>C or m.11778G>A. CONCLUSIONS/SIGNIFICANCE: Our current study provided a comprehensive profile regarding the mtDNA variation and background of Chinese patients with LHON and m.14484T>C. Matrilineal background might affect the expression of LHON in Chinese patients with m.14484T>C.

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Mitochondrial DNA sequence variation in single cells from leukemia patients.

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Mitochondrial DNA sequence variation in single cells from leukemia patients.

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