Sequence (site) heteroplasmy is the presence of mtDNA molecules that have different nucleotides at the same address. For example, an electropherogram from a heteroplasmic hair might show both T and C at position 16,093. In a blood sample from the same individual, position 16,093 could show T or C, or T and C. A failure to exclude would be scientifically supported if the blood had any of these three possibilities, because the blood and hair share a common base at every position, including the heteroplasmic position.

If T and C are present in both hair and blood, the failure to exclude is actually strengthened because the heteroplasmy is in both samples.

Back Forward