Exonic splicing enhancer

An exonic splicing enhancer (ESE) is a DNA sequence motif consisting of 6 bases within an exon that directs, or enhances, accurate splicing of hetero-nuclear RNA (hnRNA) or pre-mRNA into messenger RNA (mRNA).

The Basics
The central dogma of molecular biology states that all of the information that makes you unique is housed in the nucleus of every cell in your body in the form of DNA. The human DNA is a string of 3.2 billion base pairs. Short sequences of DNA are transcribed to RNA; then this RNA is translated to a protein. A gene located in the DNA will contain introns and exons. Part of the process of preparing the RNA includes splicing out the introns, sections of RNA that do not code for protein. The presence of exonic splicing enhancers is essential for proper identification of splice sites by the cellular machinery.

Research
Computational methods were used to identify 238 candidate ESEs. ESEs are clinically significant because synonymous point mutations previously thought to be silent mutations located in an ESEs can lead to exon skipping and the production of a non functioning protein.

Disruption of an exon splicing ehancer in exon 3 of MLH1 gene is the cause of HNPCC (human non polyposis colorectal cancer) in a Quebec family.

There is evidence that these 236 hexamers that signal splicing are evolutionarily conserved.