- Course Introduction
- 01: Evidence & DNA
- 02: Forensic Biology
- 03: DNA Extraction & Quantitation
- 04: DNA Amplification
- 05: Amplified DNA Product Separation
- 06: STR Data Analysis & Interpretation
- 07: Population Genetics & Statistics
- 08: Communicating Results
- 09: Other DNA Markers & Technologies
- Course Resources
- Laboratory Training Manual
President's DNA Initiative
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Advancing Justice Through DNA Technology
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Advancing Justice Through DNA Technology
DNA Analyst Training
Heteroplasmy and Mutations
Home > Other DNA Markers & Technologies > Non-Nuclear DNA Markers > Mitochondrial DNA > Heteroplasmy and Mutations
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Heteroplasmy is when an individual exhibits more than one mtDNA type. This phenomenon is usually observed as a single difference at one position exhibiting either two or more bases or a length difference often seen in a polycytosine rich region (C-stretch). Single base heteroplasmy has been documented, most notably in the identification of Tsar Nicholas II.15 Length heteroplasmy in the D-loop region has been described in both HV1 and HV2.16, 17, 18 Whereas heteroplasmy may complicate interpretation, it actually becomes a ‘signature’ of the donor’s mtDNA haplotype. Heteroplasmy can therefore, strengthen the identification of a sample.
Point mutations or deletions in mtDNA usually increase with age. Defects in mitochondrial function produce a wide range of human diseases and can be caused by mutations within the mtDNA. The first mtDNA mutation discovered to be the cause of a disease was Leber’s hereditary optic neuropathy (LHON).19 Identified in 1988, LHON is a maternally inherited form of adult-onset blindness due to death of the optic nerve. Point mutations are relevant because the person’s mtDNA type can change with age.
