Phenylketonuria, or PKU, is a rare inborn error of metabolism caused by a defect in the PAH gene that prohibits the correct production of an enzyme needed to process the amino acid phenylalanine.  If detected at birth a full and normal life is possible by modifying the intake of this one amino acid. If undetected, the individual inexorably declines cognitively, and behaviorally.

Philip Reilly, MD, describes in his book ORPHAN, The Quest to Save Children with Rare Genetic Disorders, his meeting of two sisters, institutionalized for PKU this way,

Carol was born in the fall of 1958; Nancy was born in 1960. Both were tall, slender, attractive women with naturally blond hair and light-blue eyes. From a distance one might believe that they were twins. Both women were also profoundly mentally retarded, with IQ scores below 50. Neither one could speak or care for herself. Both were extremely anxious in the presence of everyone (including me), except for their elderly parents, who visited them occasionally on Sunday afternoons, and the poorly paid Haitian caregivers who dressed and fed them each day. Carol and Nancy are among the last few people born in the United States who bear the full burden of a rare single-gene disorder called phenylketonuria (PKU). 

He had the opportunity to meet the parents of these women.  Dr. Reilly writes,

I still remember the father’s tears. About his wife and himself, he said, “We live with unending sorrow.”

In 1920, Pearl S. Buck’s only biological child Carol, was born. Her beautiful baby, who she joyously welcomed began to decline for unknown reasons.   Pearl searched for answers even travelling from China to the Mayo clinic to seek help for her child The baby featured in her book, The Good Earth, honors her daughter. The proceeds from the book were used to endow lifelong care for the child in the best institution her mother could find.  Before her death, the author finally learned the cause of her daughter’s profound mental decline: PKU

About 1958 the first low PHE infant formula for infants was developed. By 1968 universal newborn screening was in place in the USA, UK, and EU.

 But what is new in PKU?

• Better low PHE foods
• Six or more biotech companies working on developing gene therapy
• Kuvan and Palynzig, two medications that can allow some people with PKU to eat a more normal diet. Unfortunately, not everyone responds as well to them

PKU still requires a lifelong special diet. PKU still requires monitoring. PKU is still a burden to individuals and to families, but the accomplishments of those living with PKU is a celebration of overcoming, a celebration of the many minds who have contributed to research, and a celebration of the human spirit.

Where can families find support:  The National PKU Alliance

And a number of the biotech companies working in this area also have resources for families.

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