Maternity testing using mitochondrial DNA analysis.

We examined the maternal relationship in two cases using mitochondrial DNA (mtDNA) analysis. The hypervariable region, HVI in the displacement loop (D-loop) region, was amplified and sequenced. Samples from both cases showed the nucleotide replacements of A to C at positions 16,182 and 16,183, and T to C at position 16,189, giving rise to a C-stretch from position 16,182 to 16,193, in which twelve Cs continued. We were unable to read the region after the C-stretch by forward sequencing in both cases, and it was thought that heteroplasmy was the reason for this. However, there were other identical nucleotide replacements in addition to the C-stretch in both cases. Additionally, nucleotide sequencing was used successfully to demonstrate complete maternal inheritance in all the offspring of eight families over two or three generations. We were therefore able to confirm the maternal relationship in the two present cases, and accordingly we consider that mtDNA sequencing is a very useful method for examining the maternal relationship, especially in cases where the father is not available.