Transduction-specific ATLAS reveals a cohort of highly active L1 retrotransposons in human populations

Long INterspersed Element-1 (LINE-1 or L1) retrotransposons are the only autonomously active transposable elements in the human genome. The average human genome contains ∼80-100 active L1s, but only a subset of these L1s are highly active or 'hot'. Human L1s are closely related in sequence, making it difficult to decipher progenitor/offspring relationships using traditional phylogenetic methods. However, L1 mRNAs can sometimes bypass their own polyadenylation signal and instead utilize fortuitous polyadenylation signals in 3' flanking genomic DNA. Retrotransposition of the resultant mRNAs then results in lineage specific sequence "tags" (i.e., 3' transductions) that mark the descendants of active L1 progenitors. Here, we developed a method (Transduction-Specific Amplification Typing of L1 Active Subfamilies or TS-ATLAS) that exploits L1 3' transductions to identify active L1 lineages in a genome-wide context. TS-ATLAS enabled the characterization of a putative active progenitor of one L1 lineage that includes the disease causing L1 insertion L1RP , and the identification of new retrotransposition events within two other "hot" L1 lineages. Intriguingly, the analysis of the newly discovered transduction lineage members suggests that L1 polyadenylation, even within a lineage, is highly stochastic. Thus, TS-ATLAS provides a new tool to explore the dynamics of L1 lineage evolution and retrotransposon biology.

Choriocarcinoma-presenting as a primary lesion of the cervix

A 25 year old nulliparous Russian lady presented to the hospital complaining of abdominal pain and mild vaginal bleeding. In 1999 she was diagnosed with a molar gestation and required a dilatation and curettage. On this occasion, Beta human Chorionic Gonadotrophin (BhCG) levels were elevated and a trans-vaginal ultrasound scan suggested the presence of a left-sided pelvic mass. Investigations confirmed the presence of a choriocarcinoma of the cervix. Complete assessment by a multidisciplinary team was performed and chemotherapy (methotrexate) was commenced. This case of a twenty-five year old nulliparous woman highlights the importance of appropriate follow-up in cases of irregular genital tract bleeding with a past history of trophoblastic disease.

Ethics in the OR: DNR and patient autonomy

Suspending Do Not Resuscitate (DNR) orders during surgery may undermine a patient's right to self-determination. A Nursing Ethics Committee together with a Clinical Ethics Committee formulate guidelines to consider when suspending or maintaining a patient's DNR order while in the operating room. A patient's autonomy must be recognized as well as the professional responsibilities of surgeons, anesthesiologists and nurses.