MT-TF: MT-TF is a mitochondrially encoded tRNA phenylalanine gene that is essential for protein synthesis [PMC6571852]. In a study by (77), it was found that workers with high blood chromium levels exhibited hypomethylation of MT-TF and MT-RNR1 genes [PMC9986591]. These genes play important roles in mitochondrial function and protein synthesis. The D-loop promoter, which is involved in the initiation of transcription for the entire mitochondrial genome, was also found to have lower levels of methylation in workers with high chromium exposure [PMC9986591]. The study by (77) was the first to investigate mitochondrial DNA methylation in relation to chromium exposure, providing important insights into the epigenetic effects of chromium on mitochondrial gene regulation [PMC9986591]. The findings suggest that exposure to chromium may lead to alterations in DNA methylation patterns, specifically affecting genes involved in protein synthesis and transcription initiation within mitochondria [PMC9986591]. Further research is needed to fully understand the mechanisms underlying these epigenetic changes and their potential implications for human health [PMC9986591].