What is CDH1?

One gene in our body is called CDH1. As described by Professor Guilford, the CDH1 gene encodes a protein called E-cadherin (there are about 20,000 genes in the human genome and they each encode one protein. The genes are the instructions and the proteins do the work in the cell).

E-cadherin acts as a bridge between neighbouring cells; it therefore helps keep cells close together and communicating,  and enables stress or strain in a tissue (e.g.. stomach) to be spread over a wide area.

A mutation in the CDH1 gene stops E-cadherin from working.  Fortunately, because you have two copies of every gene (one from Mum one from Dad), the inherited mutation doesn’t initially affect the function of a cell.  However, cancer will start developing when a cell in the body (stomach or breast) loses the function of the 2nd copy (we call this the 2nd hit).  When a cell has no E-cadherin, it no longer attaches to neighbouring cells properly and looses its normal regulatory signals; as a result it starts to grow in the wrong place and out of sync with the rest of the stomach.  If left alone, it will start to get more mutations in other genes and begin to grow extremely fast.

Those who carry the CDH1 gene mutation have hereditary diffuse cancer syndrome. If someone has hereditary diffuse gastric cancer syndrome, then each child he or she has will have a 50% chance of inheriting the CDH1 mutation.