Mitochondrial DNA variation in human evolution and disease

Analysis of mitochondrial DNA (mtDNA) variation has permitted the reconstru ction of the ancient migrations of women. This has provided evidence that o ur species arose in Africa about 150 000 years before present (YBP), migrat ed out of Africa into Asia about 60 000 to 70 000 YBP and into Europe about 40 000 to 50 000 YBP, and migrated from Asia and possibly Europe to the Am ericas about 20 000 to 30 000 YBP. Although much of the mtDNA variation tha t exists in modern populations may be selectively neutral, studies of the m ildly deleterious mtDNA mutations causing Leber's hereditary optic neuropat hy (LHON) have demonstrated that some continent-specific mtDNA lineages are more prone to manifest the clinical symptoms of LHON than others. Hence, a ll mtDNA lineages are not equal, which may provide insights into the extrem e environments that were encountered by our ancient ancestor, and which may be of great importance in understanding the pathophysiology of mitochondri al disease. (C) 1999 Elsevier Science B.V. All rights reserved.