The Type I mutation is the rarest. The blank portion of a gene is normally cut out before it is translated to make a protein. Without the right coding sequence. The Type II mutation is the most common and leads to the most severe bleeding disorder. Subsequently the RNA stops adding amino acids to the PTA protein chain prematurely.
Nonfunctional protein is formed and again, the blood coagulation pathway fails.
This switch leads to the breakdown of the protein structure and once again, the coagulation pathway breaks down. Further study of the various mutation types have shown that of the various possible combinations. In other words, the Type II mutation leads to more severe problems and the severity of any disorder is proportional to the presence of the type II mutation. This is because type II individuals make less PTA than Type III individuals. It is easy to see why some individuals are more severely affected depending on what mutation types they harbor.