Human LINE-1 retrotransposable elements are members of a family of DNA elements that have been present in eukaryotic genomes for over 600 million years. They are capable of making new copies of themselves and inserting into new genomic loci. By amplifying themselves in this way, LINE-1 elements have come to make up about 15% of human DNA. The vast majority of LINE-1 sequences are mutated and are immobile; however, ±100 elements in the average human genome retain the ability to "jump" to new locations. On occasion, these "jumps" can result in various genetic diseases, including Hemophilia A, muscular dystrophy, and colon cancer. DNA methylation within the promoter region of human LINE-1 (L1) elements is important for maintaining transcriptional inactivation and for inhibiting L1 transposition.

LINE elements are highly repetitive sequences, 6K-8K base pairs in length, which contain RNA polymerase II promoters. They also have an open reading frame that is related to the reverse transcriptase of retroviruses but they do not contain LTRs (long terminal repeats).

PyroMark LINE-1 assay detects the level of methylation in pos 305 to 331 in the LINE-1 transposon (Acc no X58075).

The pyrogram shows the result from a normal blood donor DNA sample.