From PKU to Tandem Mass Spectrometry: Dr. Edwin Naylor speaks about the evolution of newborn screening technology
Dr. Edwin Naylor, now the President of NeoGen Screening, is a 30-year veteran of the newborn screening field. We asked him about his experience in working with the late Dr. Robert Guthrie, who discovered the blood spot test for phenylketonuria (PKU) in 1960. PKU is the result of an inability to break down the amino acid phenylalanine, and can cause mental and motor retardation if untreated. We also learned about the use of tandem mass spectrometry (MS/MS) for supplemental newborn screening.
Q. What insights can you share about Dr. Guthrie’s work and his discovery?
A: Bob was the father of a retarded son and an uncle to a child with PKU. However, he was not a geneticist. Prior to his work with PKU prevention, Bob was working in the area of cancer research and metabolic inhibitors. Over an informal discussion with a colleague, it occurred to him that the process he was using could be reversed to determine if phenylalanine was present. He started working with blood spots and, by the end of the next day, the PKU test was complete.
Q. What was it like to be working with the ‘Father of PKU Screening’, and how did the PKU test come to be mandated so quickly?
A: I once read an article about a commonality among winners of the Nobel Prize. All the Laureates had an intense focus and incredible drive. That was what Bob was like when it came to newborn screening. He wanted to make sure that this test was taken advantage of to detect PKU and prevent retardation. Elevating the standard of medical care involves working through extensive channels and physicians’ groups. He wasn’t going to wait that amount of time. Bob’s passion came from being a parent advocate. Bob worked with the National Association for Retarded Children (later changed to the National Association for Retarded Citizens), who drafted the model legislation and used public pressure to get the test for PKU mandated.
Q. So, what was next for Dr. Guthrie?
A: Bob didn’t spend much time in the lab after that point. Once he made that discovery, he made it his mission to share it. He was like a traveling salesman, literally promoting newborn screening around the world. Those of us who were working in his circle at the time stopped associating telephone calls in the middle of the night with emergencies. More often than not, it was Bob. It didn’t occur to him to think that the person on the other end was in another time zone.
Q. In the US, what advancement was next for newborn screening?
A: Tests for disorders that required the use of bacterial assays could be easily added. It became more complicated when congenital hypothyroidism (CH) required a radioimmunoassay and, later, an enzyme immunoassay. Testing for CH required, essentially, a clinical chemistry laboratory.
Q. And, what was next for you, Dr. Naylor?
A: After a two-year fellowship with Bob at Buffalo Children’s Hospital, I worked with him as a research associate for an additional 10 years. In 1984, I moved to Magee-Women’s Hospital to start a research program and, in 1985, established the concept of supplemental newborn screening. This lab came to be used by hospitals across the state that wanted to offer the supplemental screens that went beyond the panel decided by the state. In 1992, Don Chace, who was at Duke University at the time, and is now with NeoGen Screening, applied the use of tandem mass spectrometry (MS/MS) for newborn screening. I started training with him and convinced Magee to purchase the technology so we could bring it to benefit babies in Pennsylvania. Before long, we were using MS/MS to screen 45,000 newborns in the state and required another spectrometer. The hospital wasn’t able to purchase another machine, so I started an entrepreneurial venture. NeoGen Screening spun off as a private laboratory in 1994.
Q. In simple terms, what is tandem mass spectrometry?
A: A newborn blood specimen contains thousands of molecules ranging from those as small as salt to larger proteins such as hemoglobin. When alcohol is added to a dried blood spot, several hundred molecules are pulled out and can be studied. A tandem mass spectrometer is a specialized instrument that detects molecules by electronically measuring their weight (mass). A mass spectrum is a graph that shows exactly how much of each specific molecule is present.
Q. What advantages does MS/MS provide in newborn screening?
A: Older testing methods require the use of several tests to look at different types of molecules. Each of these tests is expensive and time consuming. Certain inborn errors of metabolism must be treated immediately to assure a newborn’s care. With MS/MS, the results are available with a single test that takes approximately two minutes. Moreover, when very different diseases have elevated levels of common chemicals, MS/MS allows one to identify specific disorders. We monitor about 60 chemical relationships in any given test, and obtain markers that provide indicators for disease, quality assurance and potential contaminators that may interfere.
Q. What’s on the horizon for NeoGen Screening?
A: Through a grant from the National Institute of Child Health and Human Development, we are working on a test for adrenoleukodystrophy (ALD). This degenerative brain disease is passed from mother to son on the X chromosome. It was made known to the public with the film Lorenzo’s Oil. While recent research has yet to find a cure, experts now believe that the fats extracted from olive oil and rapeseed oil can be effective in treating ALD boys who have yet to show symptoms. Because no testing has been performed, there is no way of estimating how many boys might be affected. It may be as common as PKU.
NeoGen Screening contracts with various hospitals and provides supplemental screenings for various states’ and countries’ newborn screening programs. Individual health care providers and parents can arrange to obtain services directly. To date, blood samples from nearly one and a half million children have been screened at this laboratory.