Mutations in mtDNA have accumulated sequentially, and maternal lineages have diverged to form population-specific genotypes. Classification of the genotypes has been made based on differences found in restriction fragment analysis of the coding region or in the sequence of the hypervariable segment I.

The evolution of the human mitochondrial genome is characterized by the emergence of ethnically distinct lineages or haplogroups.

Nine European, seven Asian (including Native American), and three African mitochondrial DNA (mtDNA) haplogroups have been identified previously on the basis of the presence or absence of a relatively small number of restriction-enzyme recognition sites or on the basis of nucleotide sequences of the D-loop region.

There are phylogenetic relationships among mitochondrial genomes described elsewhere from the major human ethnic groups.

 There were numerous instances both of parallel mutations at the same site and of reversion (i.e., homoplasy). It is likely that homoplasy in the coding region will confound evolutionary analysis of small sequence sets. (#11938495#)

Haplogroups

 Haplogroup A
 Haplogroup B
 Haplogroup C
 Haplogroup D
 Haplogroup E
 Haplogroup F
 Haplogroup G
 Haplogroup H
 Haplogroup I
 Haplogroup J
 Haplogroup K
 Haplogroup L
 Haplogroup M
 Haplogroup N
 Haplogroup O
 Haplogroup P
 Haplogroup Q
 Haplogroup R
 Haplogroup S
 Haplogroup T
 Haplogroup U
 Haplogroup V
 Haplogroup W
 Haplogroup X

Localized haplogroups

 african haplogroups

• Haplogroup L
   native americans haplogroups
• Haplogroup A
• Haplogroup B
• Haplogroup C
• Haplogroup D

Diffuse haplogroups

 Haplogroup X

References

 Herrnstadt C, Elson JL, Fahy E, Preston G, Turnbull DM, Anderson C, Ghosh SS, Olefsky JM, Beal MF, Davis RE, Howell N. Reduced-median-network analysis of complete mitochondrial DNA coding-region sequences for the major African, Asian, and European haplogroups. Am J Hum Genet. 2002 May;70(5):1152-71. Epub 2002 Apr 5. PMID: #11938495#

 Richards M, Macaulay V. The mitochondrial gene tree comes of age. Am J Hum Genet. 2001 Jun;68(6):1315-20. PMID: #11349234#