In human genetics, a human mitochondrial DNA haplogroup is a haplogroup defined by differences in human mitochondrial DNA. In human genetics, the haplogroups most commonly studied are Y-chromosome (Y-DNA) haplogroups and mitochondrial DNA (mtDNA) haplogroups, each of which can be used to define genetic populations. This tree shows the age (YBP) of different mtDNA haplogroups. At EMPOP, the tool haplogroup browser represents all the established Phylotree haplogroups in convenient searchable format and provides the. All members of a haplogroup trace their ancestry back to a single. A maternal haplogroup is a family of mitochondrial DNA (mtDNA) that traces back to a single common ancestor.