In the late 1970’s, a rare metabolic disorder called “Phenylketonuria” (PKU) was little known by the medical community. With this condition, a liver enzyme is missing, preventing the body from properly breaking down protein rich foods, which becomes toxic to the body. As the brain develops, high levels of "phenylalanine" can lead to severe intellectual hinderance, neurological conditions, and a failure to thrive. Everyone is tested for PKU shortly after birth, as it is passed on genetically. The doctors, still, remained uncertain if the new treatment — a diet and strict blood monitoring — would work. What was this strange disorder, which prevented people from eating healthy foods?

Award-winning author A.L. Mengel was one of the first babies placed on the experimental treatment program, a protein restricted diet. His parents, in defiance of the doctors, insisted he also be given breast milk, for the necessary cerebrosides for proper brain development. It was not recommended, due to the risk of the emergence of protein toxicity. A.L. Mengel is one of the first success stories, demonstrating his family's perseverance not only in the construction of his mind, which allowed him to function as a productive member of society, but also giving him a chance to pursue an extraordinary journey as an Award-Winning author.

The chances of success weaved uncertainty throughout Mengel's life, as there remains no cure. Three Letters is their story. The book tells the story of how his family beat the odds of a mysterious disorder which shows that one’s challenges must be broken through to follow a dream.