Three Letters : My Journey with Phenylketonuria

by A.L. Mengel

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.

455 pages, Kindle Edition

Published December 9, 2025

About the author

A.L. Mengel is an Award-Winning Author of Speculative Fiction. His novels and stories have each been called a "complex examination of relationships" with characters on a journey of transformation. He writes in the Supernatural, Paranormal and Science Fiction genres. Mengel novels are typically deep, philosophical, and thought provoking.

His works address issues of alcoholism, intolerance, grieving and death, fear of the afterlife, and the journey for understanding, among others. His protagonists, some of which are angels and demons, are frequently found on a search for purpose or transformation, which are recurring themes in his stories.

Mengel grew up reading Stephen King and Anne Rice, two of his favorite authors. He first found a love of writing upon taking a Creative Writing class in High School - but did not become a more serious writer until becoming an Arts and Entertainment Editor in Philadelphia, and later while taking another Creative Writing class where he was inspired to complete his first novel. More recently, he has connected and interacted with his readers via "The Writing Studio" where he shares his writing methods and inspiration. He enjoys time with his two dogs and two cats, and loves to write outdoors as much as possible.

Reviews

[Dakota Summers · Rating 5 out of 5]

Buckle up! You are now in the world of A.L. Mengel as he reflects on his journey of living with Phenylketonuria. Three Letters takes you through a life of lessons and love as A.L. Mengel shares his experience growing up with the condition. The struggles he faces are met with humility, confidence, and astounding support from his family. As someone with a family member who has PKU, Three Letters was a fantastic resource for me to read. I gained an excellent understanding Phenylketonuria. I learned about the challenges someone with PKU will encounter and greatly enjoyed the stories A.L. Mengel shared. I would highly recommend this book to anyone who has Phenylketonuria or knows someone with the condition, also known as PKU.

[Jerry · Rating 5 out of 5]

I honestly didn't know what to expect from this one. It's so different from the other books. But I have to tell you it had me turning the pages. I didn't know he had such a difficult journey. Plus the ending was incredible. Probably his best book of all time.

[Chaucy Prime · Rating 5 out of 5]

I could not put this one down. Beautifully written.