To find out more information on the basic genetics of Porphyria visit:
Basic genetics: http://learn.genetics.utah.edu/content/basics/
Mutations: http://learn.genetics.utah.edu/content/basics/mutation/
Dominance/recessive: http://learn.genetics.utah.edu/content/basics/patterns/
Genetic variation: http://learn.genetics.utah.edu/content/basics/outcome