A FAMILY EXHIBITING HETEROPLASMY IN THE HUMAN MITOCHONDRIAL-DNA CONTROL REGION REVEALS BOTH SOMATIC MOSAICISM AND PRONOUNCED SEGREGATION OFMITOTYPES

A family exhibiting heteroplasmy at position 16355 in hypervariable re gion I of the human mtDNA control region has been identified. This fam ily consists of a mother, daughter, and son. DNA samples extracted fro m blood stains, buccal swabs, and hairs from these individuals were am plified by PCR and sequenced utilizing fluoresence-labeled dye termina tor chemistry in an automated DNA sequencer. In both the daughter and mother, heteroplasmy was observed in DNA extracted from blood stains, buccal swabs, and hairs. In the blood stains, the proportion of cytosi ne was greater than thymine in both individuals. Buccal swab extracts showed a more balanced contribution from the two nucleotides. Telogeni c hair root and hair shaft samples exhibited a wide range of nucleotid e contributions at this position, from predominately cytosine in some samples to predominately thymine in others. The apparent stochastic se gregation of mitotypes in hair samples is discussed from a forensic vi ewpoint, and the mechanism of mtDNA heteroplasmy is considered.