Abstract

Genome variations in the form of single nucleotide polymorphism, INDELs (insertions or deletions) and, duplications, inversions and copy number variations are more widely prevalent than initially predicted. Mitochondrial tumor suppressor gene maps on chromosome 8p, in which exon 4-specific deletion is associated with susceptibility towards breast and various other forms of cancer. In this study, 41 head and neck cancer, 15 breast cancer patients and 280 healthy control individuals were analyzed for mitochondrial tumor suppressor gene copy number variation. The frequencies of wt/wt (homozygous wild-type), wt/Del (heterozygous variant) and Del/Del (homozygous deletion variant) mitochondrial tumor suppressor gene genotypes were found to be 73.3%, 26.7%, and 0% in breast cancer patients, 41.5%, 58.5%, and 0% in head and neck cancer patients and 43%, 57%, and 0% in healthy individuals, respectively. A significant association of the deletion variant with breast cancer (odds ratio = 0.27, 95% confidence interval = 0.08–0.87, P = 0.0207) was found in our population. In addition, the allele and genotype frequency varied significantly (P<0.0001) among Indian and German populations, reflecting ethnic diversity. This pilot case-control study highlighted the indicative role of mitochondrial tumor suppressor gene deletion in protection from breast cancer in Indian population. However, the findings need to be investigated in larger patient sample size before any conclusive role of mitochondrial tumor suppressor gene copy number variation on cancer risk.