The analysis of heteroplasmic A189G mutation by the peptide nucleic acid/real-time polymerase chain reaction (PNA/qPCR) method produced a sensitive detection as well as reliable and reproducible quantification of mutant level. This technique showed the absence of the A189G transition in buccal cells in young persons and its presence in older individuals from the same mother, indicating that it was a mutation that could be inherited. The study demonstrated for the first time the accumulation with age of the A189G mutation in buccal cells in levels lower than 13 percent. In the cells of muscle tissues, mutation accumulation was age-related and reached high levels in individuals 60 years old or older. These results could have many implications in heteroplasmy interpretation in forensic casework and also in anthropological studies. The detection of the 189 heteroplasmic point mutation involved three technologies: automated DNA sequencing, Southern blot hybridization using a digoxigenin-labeled oligonucleotide probe, and PNA/qPCR combined method on different biological samples. 3 tables, 6 figures, and 35 references