Mitochondrial DNA (mtDNA) is a compact, double-stranded, circular molecule with a length of 16,569 bp. mtDNA typically contains about 37 genes, including 22 tRNAs and 2 rRNAs. The instability and variation of mtDNA is increasingly recognized as an important cause of a range of human diseases, such as Alzheimer's disease, Parkinson's disease, colorectal cancer, Kearns-Sayre syndrome, and so on. human mitochondrial dna sequence