Homeobox-containing genes are thought to have a role in controlling development. In Drosophila, the 'engrailed' (en) gene plays an important role during development in segmentation, where it is required for the formation of posterior compartments. Different mutations in the mouse homologs, En1 and En2, produced different developmental defects that frequently are lethal. The human engrailed homologs 1 and 2 encode homeodomain-containing proteins and have been implicated in the control of pattern formation during development of the central nervous system.
The Engrailed-2 gene encodes for the Engrailed-2 homeobox transcription factor. The signaling molecule, fibroblast growth factor 8 (FGF8), controls the expression of the En2 gene. The isthmus organizer expresses varying concentrations of FGF8 that influence the En2 transcription factor. En2 transcription factor is involved in patterning the midbrain of the central nervous system during embryonic development. Specifically, it is required for proper positioning of folia in the developing hemispheres. It continues to regulate foliation throughout nervous system development. En2 patterns cerebellum foliation in the mediolateral axis. Several birth defects can arise from inadequate or abnormal En2 expression. Scientists use a mice model to study the effects of En2 knockout alleles on development. When the En2 gene is knocked out, vermis foliation patterning becomes extremely altered. Along with decreased cerebellum foliation complexity, mutations in the En2 gene result in a depleted vermis or an overly simplified foliation pattern. The Engrailed genes are essential to proper neural circuit development.
A method for diagnosing prostate cancer by detection of EN2 in urine has been developed. The results of a clinical trial of 288 men suggest that EN2 could be a marker for prostate cancer which might prove more reliable than current methods that use prostate-specific antigen (PSA). If effective, a urine test is considered easier and less embarrassing for the patient than blood tests or rectal examinations and, therefore, less likely to discourage early diagnosis. At the time of the report, it was not clear whether or not the EN2 test could distinguish between aggressive tumours that would require intervention and relatively benign ones that would not.
The EN2 test for prostate cancer has been licensed to Zeus Scientific, as they reported in March 2013. In that announcement they said they expected the test to be submitted to the US-FDA in a year, and available worldwide in 2 years.
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