Somatic mtDNA mutations observed in Endometriosis patients¹.

1<p>Total number of mutations: 51; ²Novel mutations: 31, Reported mutations: 20;</p><p>Ref, Cambridge reference sequence; Bld, Blood; Eut, Eutopic endometrium;</p><p>Ect, Ectopic endometrium; F, Frequency of mutations; HM, Homoplasmic mutation;</p><p>HT, Heteroplasmic mutation; NPCR, Non Protein Coding Region;</p

Mitochondrial Genome Variations in Advanced Stage Endometriosis: A Study in South Indian Population

<div><h3>Background</h3><p>Endometriosis is a chronic gynecological benign disease that shares several features similar to malignancy. Mitochondrial DNA (mtDNA) mutations have been reported in all most all types of tumors. However, it is not known as to whether mtDNA mutations are associated with endometriosis.</p> <h3>Methodology</h3><p>We sequenced the entire mitochondrial genome of analogous ectopic and eutopic endometrial tissues along with blood samples from 32 advanced stage endometriosis patients to analyze the role of somatic and germ-line mtDNA variations in pathogenesis of endometriosis. All ectopic tissues were screened for tumor-specific mtDNA deletions and microsatellite instability (MSI). We also performed mtDNA haplogrouping in 128 patients and 90 controls to identify its possible association with endometriosis risk.</p> <h3>Principal Findings</h3><p>We identified 51 somatic (novel: 31; reported: 20) and 583 germ-line mtDNA variations (novel: 53; reported: 530) in endometriosis patients. The A13603G, a novel missense mutation which leads to a substitution from serine to glycine at the codon 423 of ND5 gene showed 100% incidence in ectopic tissues. Interestingly, eutopic endometrium and peripheral leukocytes of all the patients showed heteroplasmy (A/G; 40–80%) at this locus, while their ectopic endometrium showed homoplasmic mutant allele (G/G). Superimposition of native and mutant structures of ND5 generated by homology modeling revealed no structural differences. Tumor-specific deletions and MSI were not observed in any of the ectopic tissues. Haplogrouping analysis showed a significant association between haplogroup M5 and endometriosis risk (<em>P</em>: 0.00069) after bonferroni correction.</p> <h3>Conclusions</h3><p>Our findings substantiate the rationale for exploring the mitochondrial genome as a biomarker for the diagnosis of endometriosis.</p> </div

Mitochondrial haplogroup distribution in endometriosis patients and controls¹.

1<p>Haplogroups observed = 39; ²Banferoni correction for <i>P</i>-value = 0.05/39 = 0.00128.</p

The ‘A13603G’ mutation of ND5 gene.

<p>(A) Sequence analysis of ‘A13603G’ mutation using a forward primer. Homoplasmic wild (13603A) and mutant alleles (13603G) appear as single peaks whereas heteroplasmic allele (13603A/G) as double peak. Evolutionary conservation analysis of mutation is also shown. CT: Control, CS: Case, BLD: Blood, EUT: Eutopic endometrium, ECT: Ectopic endometrium; (B) Native structure of ND5 subunit: ‘serine 423’ is shown as a blue sphere; (C) Ramachandran plot showing the structural accuracy of native structure of ND5 subunit: all the amino acids are in the allowed region except proline and glycine; (D) Mutated structure of ND5 subunit: ‘glycine 423’ is shown as a green sphere; (E) Superimposition of native (green) and mutant (red) structures of ND5 subunit.</p

Novel missense mtDNA mutations observed in endometriosis patients¹.

1<p>Total number of mutations: 18; ²Germ-line mutations: 11, Somatic mutations: 7; ³Conservation; Ref, Cambridge reference sequence.</p><p>Bld, Blood; Eut, Eutopic endometrium; Ect, Ectopic endometrium; F, Frequency of mutations; PC, Poorly conserved; HC, Highly conserved; CN, Conserved.</p

Mitochondrial Control Region Alterations and Breast Cancer Risk: A Study in South Indian Population

<div><p>Background</p><p>Mitochondrial displacement loop (D-loop) is the hot spot for mitochondrial DNA (mtDNA) alterations which influence the generation of cellular reactive oxygen species (ROS). Association of D-loop alterations with breast cancer has been reported in few ethnic groups; however none of the reports were documented from Indian subcontinent.</p><p>Methodology</p><p>We screened the entire mitochondrial D-loop region (1124 bp) of breast cancer patients (n = 213) and controls (n = 207) of south Indian origin by PCR-sequencing analysis. Haplotype frequencies for significant loci, the standardized disequilibrium coefficient (D′) for pair-wise linkage disequilibrium (LD) were assessed by Haploview Software.</p><p>Principal Findings</p><p>We identified 7 novel mutations and 170 reported polymorphisms in the D-loop region of patients and/or controls. Polymorphisms were predominantly located in hypervariable region I (60%) than in II (30%) of D-loop region. The frequencies of <i>310‘C’</i> insertion (<i>P</i> = 0.018), <i>T16189C</i> (<i>P</i> = 0.0019) variants and <i>310‘C’ins/16189C</i> (<i>P</i> = 0.00019) haplotype were significantly higher in cases than in controls. Furthermore, strong LD was observed between nucleotide position 310 and 16189 in controls (D′ = 0.49) as compared to patients (D′ = 0.14).</p><p>Conclusions</p><p>Mitochondrial D-loop alterations may constitute inherent risk factors for breast cancer development. The analysis of genetic alterations in the D-loop region might help to identify patients at high risk for bad progression, thereby helping to refine therapeutic decisions in breast cancer.</p></div

Linkage disequilibrium (LD) analysis of significant D-loop SNPs in cases and controls:

<p>Haploview plots are presented along the single nucleotide polymorphisms studied. The pair-wise linkage disequilibrium values (D′ = 0–100) of all significant SNPs are given in each diamond. A value of 100 represents maximum possible linkage disequilibrium.</p

Novel mutations detected in mitochondrial D-loop region of breast cancer patients.

<p>rCRS: Revised Cambridge Reference Sequence.</p><p>IUPAC: International Union of Pure and Applied Chemistry.</p

Novel mutations observed in D-loop region of breast cancer patients:

<p>(A) 12 ‘C’ insertion; (B) A37G transition; (C) A238G transition; (D) C463T transition; (E) C566G transversion; (F) T16445C transition; (G) G16485A transition.</p

Graphical representation of minor allele frequencies of significant D-loop SNPs in breast cancer patients with different clinical parameters:

<p>(A) breast cancer stage; (B) menopausal status; (C) estrogen receptor status; (D) progesterone receptor status; (E) human epidermal growth factor receptor 2 status. Asterisk (*) indicates the significant difference (<i>P</i><0.05, as determined by the Student’s t-test) between patient groups with different clinical parameters. Percentage values were used for statistical analysis.</p