If you were to ask any physician trained in the US in the last thirty years about phenylketonuria (PKU) they would probably tell you that PKU is a treatable inherited disease screened for at birth. This is true in this country today. But the reality is that the treatment for PKU goes hand in hand with the early detection of this disorder by newborn screening. Without newborn screening, PKU is a very different disease.
PKU is chronic progressive disorder that devastates the brain and central nervous system over time – a fact that the Baby Genes lab was reminded of this week.
The sample came from a hospital in the Midwest with a minimal amount of medical records – a ten year old girl with seizures, developmental delay, severe muscle wasting who was non-verbal and non-ambulatory, The child and her family had recently moved to the US from the Middle East. The family had a total of five children including another sibling who also had seizures and developmental delays. The patient had been normal at birth. She developed slowly and started having seizures at 5 months of age. An MRI done at that time had no significant findings. The family moved to the US two years ago and the patient was referred to clinic because of a worsening of her seizures. The patient’s current neurologist who saw the patient ordered an MRI which revealed significant changes to the white matter in the brain. A blood sample was collected and sent to Baby Genes for DNA analysis. Test results provided in 96 hours. To everyone’s surprise, DNA testing revealed two mutations in her PAH gene. She has PKU – untreated PKU.
In the United States, we have the luxury of forgetting about the devastation that can come from not treating this disorder. The availability of newborn screening, access to healthcare and health care professionals all ensure that infants with PKU in the US start life with the best opportunity for health. The situation in countries outside of the United States can be very different – with devastating consequences. Had this child been born in the United States, she would have had newborn screening at birth. Had her disorder been diagnosed early and begun treatment before symptoms, she may have lived a normal life. The lack of newborn screening led to a very different and tragic path.
While her diagnosis late in life was a missed opportunity, starting treatment now still has benefits. The patient has been started on a low protein diet and her parents have noticed improvements in her behavior and a lessening of her seizures. Additionally, the results of this DNA test has provided her family with information about her health, the causes of her problems and information for other family members about their own risks.
We should always remember that newborn screening saves lives.
Kathleen Fergus, Genetic Counselor