In the Hunger Games book there were genetically mutated 'Mutts' also called 'Muttations', which were the actual dead tributes. They made these mutts by mutating their cells and adding the cells of a wolf, morphing their bodies! They can stand on their hind legs like a human, and had the same eye color as the body originally being mutated. Through my research I found, of course, humans cannot be mutated into mutts, and I also found some facts that might catch your eye!
Genetic mutations can be horrible or completely harmless. What are mutations you ask? Mutations are permanent changes in the sequence that makes a gene. (What is a gene mutation and how do mutations occur? - Genetics Home Reference ) I have found some information that explains further on how these mutations happen in the real world.
Ultra violet light, nuclear radiation, and certain chemicals can harm cells in the body and cause them to make new proteins that might function differently in the body, which may cause a mutation. Also DNA bases (Guanine, Cytosine, Adenine, Thymine) copy themselves. If these DNA bases get copied and and mixed with the wrong matching base it can also cause a mutation in the DNA.
("What Causes DNA Mutations?") DNA bases are meant to be in a organized fashion ex: Cytosine and Guanine are a pair. Guanine and Cytosine do not go together with Adenine and Thymine. But Thymine goes with Adenine and not with Guanine, and Cytosine.
There are two different types of mutations. They are inherited mutations, and acquired mutations. ("Types of mutations"). [I will only explain what Acquired mutations are because this is what I believe the capital did to change the tributes into Mutts]. Acquired mutations are mutations that are caused by harmful elements of the Earth. Chemicals and nuclear radiation can give you a mutation such as excess body mass like tumors. It can change your body completely. Your tissues in your body can be changed in size and weight, leaving you with unusual masses of tissue. So stay away from nuclear plants and high amounts of radiation! In the Hunger Games, I believe that the Mutts were given their mutations, because the Capitol injected wolf cells into their bodies.
I also found a story that I think is ridiculous, but I also think that it connects to the Hunger Games! It is about a girl who was taking care of her plants. She got pricked by a cactus. A couple days later she started growing thorns from her arm! The cactus started mutating her cells in the wound and the doctors couldn't get rid of it. She was basically being mutated into a cactus! (Terrible mutations may turn humans into plants or animals - English pravda.ru) All though I have no proof that this can't or can happen, I am very well sure that this is impossible. But don't take my word for it.
DNA - Structure. Chemguide: Helping You to Understand Chemistry - Main Menu. Jim Clark, 2007. Web. 05 Dec. 2011. <http://www.chemguide.co.uk/organicprops/aminoacids/dna1.html>.