Extensive calcification (arrow) with ossification and bone marrow elements (insert, 400×) in the thrombosed and re-canalized left anterior descending artery from the explanted heart of a 29-year-old man who suffered from Kawasaki disease at age 3 years.
These elements insert themselves into the host genome using two enzymes that they encode for themselves: an endonuclease that cleaves the host chromosome in a specified location, and a reverse transcriptase that copies the retrotransposon's DNA back into the host genome.
A chromodomain functions to recognize the heterochromatic regions when the Ty3/Gypsy-like elements insert into chromosomes [ 28, 29].
It is possible that newer CR1 elements insert throughout the genome and those that are not removed are located in GC rich regions.
If L1 elements insert at the blastocyst stage, before germline partitioning, this could generate high level somatic and germline mosaicism, with many cells sharing the same insertion and resulting in high-frequency transmission of insertions to the next generation.
For example, the R1 clade families RT and R7 have been known to specifically insert in the 28S and 18S ribosomal RNA (rRNA) genes, respectively [ 42- 45]; the Mino elements insert into AC repeats [ 45].
