DNA sequencing

In many of the techniques outlined above, no specific
information is gained about the exact nature of the alteration in
the DNA. In some cases, the change detected may turn out to
be a polymorphism that has no direct bearing on the condition
under investigation. The exception to this is the protein
truncation test (PTT), which detects mutations that shorten the
protein product and are therefore more likely to be pathogenic.
In chemical cleavage of mismatch analysis, particular types of
base mismatch are cleaved specifically by the different chemicals
employed; this yields limited information about the type of
change observed.