This is either because they cause no change in the composition of the protein that the gene encodes (some apparently different genetic words actually have the same meaning to the protein-making apparatus), or because the change they make has no effect on the protein's function.
In a manner of speaking, squash has been sexed up in a bid to make itself more attractive to the IOC, making vibrant changes to the courts and apparatus.
The Nuclear Posture Review proposes that we consider a series of options that extend presidential decision-making time, by strengthening command and control apparatus around those nuclear weapons, and that we open discussions with Russia to reduce the possibility of either an accidental launch or a false detection of a launch.