(Thanks to Sir John Burn Lynch Syndrome UK Conference 2015)
We all inherit our DNA 50% from each parent. If we have LS then one of our repair genes is good while the other one is faulty.
Think of the repair genes as two Doormen on the door at a night club. Nothing is going to get past them that shouldn’t. This is a person without LS
Imagine one of the Doormen needs the toilet and walks off. We still have one doorman watching and keeping us safe. This is a person with LS
Imagine the other doorman now needs to toilet and leaves. Nobody is now watching door. This is what happens when one good gene goes faulty for what ever reason. Anybody can just walk in now
In brief, we only have one repair gene looking out for us and if it gets damaged in a cell we are left with no protection.