Mitochondrial DNA (mtDNA) Maternal Lineage Testing
Mitochondrial DNA maternal lineage testing is used to determine whether two or more individuals are related through their mother's ancestral line. This test may be used to provide additional evidence in difficult maternity cases where the alleged mother is not available for testing or in cases where a single non-matching genetic system is observed between the alleged mother and the child in question. A single non-matching genetic variation in a maternity test is often the result of a mutation (a random change in the DNA which occurs in the formation of the egg used for conception). Since mtDNA is inherited through the maternal line, all sons and daughters inherit their mother's mtDNA. However, only daughters pass on their mother's mtDNA to their offspring. Mitochondrial DNA is composed of a string of DNA nucleotides (the 4 building blocks of DNA represented by the letters A, C, G and T) in a particular sequence. In the mtDNA maternal lineage test, a short segment of the mtDNA is sequenced (the order of DNA molecules is determined) and the mtDNA sequences from each individual are compared to see if they could come from the same maternal line. Everyone from the same maternal line will have similar mtDNA sequences. mtDNA maternal lineage testing takes much more time to complete as compared to other types of DNA paternity or maternity testing. UNTHSC is one of only a small number of labs in the country capable of performing this type of DNA testing.