- Kirsten Frankfort
- May 5, 2022
- 2 min read
What is Phenylketonuria (PKU)?
What is it?
Phenylketonuria (PKU) is a rare inherited metabolic condition in which the body cannot properly metabolize phenylalanine (‘phe’). Phe is an amino acid found in all sources of protein. People with PKU are deficient in the enzyme phenylalanine hydroxylase (PAH) which breaks down phe. Since a person with PKU lacks PAH, this causes a buildup of phenylalanine in the blood. Excess ‘phe’ causes irreparable brain damage and can lead to neurological deficits.
The Genetics of PKU
PKU is inherited in an autosomal recessive pattern. Each parent carries one defected copy of the PKU gene and one normal copy of the PKU gene. If a child receives the defected copy from both parents they are affected and have PKU (25% chance). If a child receives the defected copy from only one parent (either mother or father) and the normal gene from the other, they will be a carrier (50% chance). If a child receives the normal gene from both parents they are unaffected (25%).
Regardless of singletons, multiples, or any child conceived by the parents who both are carriers, the chances of affected, carrier, & unaffected remain the same. Also, regardless of the child's sex the chances also remain the same.
Carriers do not have any noticeable symptoms but can pass the defected gene to their offspring depending on their partners status.
How rare is rare?
World stats
7.75 billion people in the world | ~450,000 people with PKU
= 0.0058% !!
US Only Stats
3.6 million born in 2020 | PKU affects 1 in 12,000 born
300 PKU babies per year = 0.0083% !!
~16,500 people living with PKU = 0.005% !!
I'd say our PKU'ers are PHEnominally pretty rare!
How is it tested?
PKU is first detected on the newborn metabolic screen – a blood test required for every infant born in the United States.
People with PKU monitor their phe levels at home with a blood spot test on specialized filter paper which is then sent to their genetic team and lab. The goal is to maintain phe levels within a therapeutic range that research has determined has minimal side effects.
How is it treated?
PKU is an incurable lifelong disease. Treatment most often involves strict adherence to specialized ‘phe-free’ or ‘low-phe’ diets to maintain phe levels within a therapeutic safe range. Other treatment may include
daily medications (Kuvan, Palynziq)
medical formula and food
daily diet logs or counting phe
regular phe levels and lab work
growth and development monitoring
Kirstie's Key Takeaways
PKU is a rare, inherited metabolic disorder.
People with PKU cannot break down phenylalanine or 'phe', an amino acid found in all sources of protein.
Excess phe causes irreparable brain damage.
It is incurable and requires lifelong treatment and monitoring.
With early detection through the newborn screen and strict adherence to diet, many people with PKU maintain normal development and lead a healthy life.
Additional Resources
I would LOVE to hear from YOU! I believe in collaboration and sharing ideas so we can all learn and grow from each other so please drop a comment below, on Insta, or message me!
Comentários