Location and frequency of polymorphic positions in the mtDNA control region of individuals from Germany

Abstract

In order to identify polymorphic positions and to determine their frequency in the human mitochondrial D-loop containing region, the mitochondrial DNA (mtDNA) control region of 200 unrelated individuals from Germany were amplified and directly sequenced. Sequence comparison led to the identification of 190 mitochondrial lineages as defined by 202 variable positions. The most frequently occurring lineage comprised 5 individuals, whereas 186 types of D-loop sequences were observed in only one individual. Of the sequences studied 7% are not unique but show at least one counterpart with an identical haplotype. The majority (61%) of the control regions investigated showed between four and eight nucleotide positions deviating from the reference sequence. The maximum number of deviations observed in a single control region was 18. The majority of the variable positions in the D-loop region (88%) are located within three hypervariable regions. Sequence variations are caused by nucleotide substitutions, insertions or deletions. As compared to insertions and deletions, nucleotide substitutions make up the vast majority of the mutations (90%). We have predominantly found transitions (75%) and a significantly lower frequency of transversions (15%) whereas insertions (6%) as well as deletions (4%) are rather rare. Upon sequencing the mitochondrial control region from 200 German Caucasians the genetic diversity was estimated at 0.99. The probability of two randomly selected individuals from a population having identical mtDNA types is 0.6%.