FTDNA company has made the following observation on their web site:

"   It is obvious from our observation of 1000's of samples that some markers change or mutate at a faster rate than others. While that actual 'faster rate' has not yet been definitively calculated, not all markers should be treated the same for evaluation purposes.

The markers in red have shown a faster mutation rate then the average, and therefore these markers are very helpful at splitting lineages into sub sets, or branches, within your family tree.

Explained another way, if you match exactly on all of the markers except for one or a few of the markers we have determined mutate more quickly, then despite the mutation this mismatch only slightly decreases the probability of two people in your surname group who match 11/12 or even 23/25 of not sharing a recent common ancestor."

The faster mutating markers noted are:
385a, 385b, 439, 458, 459a, 459b, 449, 464a, 464b, 464c, 464d