This is the final report on the NIJ-sponsored "LINE Elements" project, whose stated goal was to "identify 'young' polymorphic Ta LINE elements and develop these elements as markers for forensic DNA profiling."
The study identified just over 140 new L1 insertion polymorphisms and determined the chromosomal location and phylogenetic distribution of each L1 element. In addition, the study identified the human genetic variation associated with the L1 insertion polymorphisms in major geographic groups. The study concluded that multiplex analysis of these loci was not reproducible as a result of the large PCR (polymerase chain reaction) amplicons that contained a significant proportion (greater than 98 percent) of nearly identical genetic material (L1 element). PCR-based screening of over 500 Alu insertion loci resulted in the recovery of a few "young" Alu elements that also resided at orthologous positions in non-human primate genomes. Sequence analysis showed that these "young" Alu insertions represented gene conversion events of pre-existing ancient Alu elements or independent parallel insertions of older Alu elements in the same genomic region. The level of gene conversion between Alu elements suggests that it has had a significant influence on the single nucleotide diversity within the genome. The study suggests that the majority of Alu insertions in primate genomes are the products of unique evolutionary events. The researchers analyzed 1,705 haplotypes based on 9 short tandem repeat (STR) loci on the Y-chromosome from 9 to 11 groups each of African-Americans, European-Americans, and Hispanics in the United States. The analysis did not find significant geographic heterogeneity among African-American, European-American, and Hispanic Y-STR and mtDNA haplotypes. This means that forensic DNA databases do not need to be constructed for separate geographic regions of the United States. Suggestions are offered for future research. Appended abstracts of research-related journal articles