The effect of somatic mutations in mitochondrial DNA on the survival of patients with primary brain tumors

Abstract

Aim: To assess the presence of mitochondrial (mt) DNA somatic mutations, determine the relationship between clinicopathological characteristics and mutations, and assess the survival outcomes in Malay patients with primary brain tumors.

Methods: The study enrolled 54 patients with primary brain tumors. DNA extracted from paired tissue and blood samples was subjected to Sanger sequencing to identify alterations in the entire mtDNA. The associations between clinicopathological characteristics and mutations were evaluated. Cox-regression multivariate analysis was conducted to identify factors significantly associated with survival, and Kaplan-Meier analysis was used to compare the survival of patients with and without mutations.

Results: Overall, 29.6% of the patients harbored 19 somatic mutations distributed across 15 loci within the mtDNA. Notably, 36.8% of these mutations were not previously documented in MITOMAP. One newly identified mutation caused a frameshift in the ATPase6 gene, resulting in a premature stop codon. Three mutations were classified as deleterious in the MitImpact2 database. Overall, 1097 mtDNA polymorphisms were identified across 331 different locations. Patients with mutations exhibited significantly shorter survival than patients without mutations.

Conclusions: mtDNA mutations negatively affected the survival outcomes of Malaysian patients with primary brain tumors. However, studies with larger samples are needed to confirm the association between mutation burden and survival rates.

Figure 1

Chromatograms of wild-types and mutations detected in patients with primary brain tumors. (A) The deletion observed at locus 8894 of ATPase6 led to a frame-shift mutation. Additionally, three other mutations of ND2 and ATPase6 were identified as having deleterious status according to MitImpact2: (B) T4705C, (C) C8897G, and (D) C8914A. Black lines represent the codon, while amino acid changes are in red.

Figure 2

Kaplan-Meier survival analysis and hazard plots were used to assess the overall survival of patients with primary brain tumors. The three-year survival associated with mutations (P = 0.035) (A), with its hazard plot (B). Blue curves: mutation; Red curves: no mutation.