When Gianni Andrada was born, a routine (and required) newborn blood test revealed that he had the genes for cystic fibrosis, a devastating disease. It took another four months for the final diagnosis to be made; it was negative.
As this story—told to the Today Show in 2011—demonstrates, genetic testing is not infallible. In fact, the number of false positive results from newborn testing is about 1/300 infants, which totals more than 13,000 such results per year in the United States alone. The story also highlights another concern: as genetic testing techniques become more sensitive and sophisticated, are public health agencies and the medical profession ready for them? This question becomes increasinly important now that more than 60 countries have adopted newborn screening programs and the technology behind screening is starting to shift toward more data-intense next-generation sequencing.
Most stories on the use of these faster, next-generation sequencing techniques focus on the success stories. We have all heard about newborns who spend months, maybe years, in and out of hospitals in search of a diagnosis. It can take weeks (or months) to get clinical results back from our current “heel prick” blood tests of newborns. So, next-generation sequencing techniques have been hailed as a faster way to arrive at answers for a larger number of diseases among newborns.
- One company offering this approach is Parabase Genomics, a Boston-based firm that is working to match genetic counselors with next-generation sequencing techniques on newborns. The company advertises tests that can deliver results on 14 disease categories within 10 days, with a rare disease follow-up test that delivers results within four weeks. The sample for these tests is the same heel prick performed for traditional newborn testing.
- Another company, Counsyl, starts a little earlier. The company tests families for propensity toward a number of inherited diseases and will test infants as young as 10 weeks old for more than 100 disorders using whole-exome sequencing techniques. The company states it has performed more than half a million DNA screens so far.
But other practitioners have some concerns.
- A group of researchers from McGill University raised concerns that whole-genome sequencing (in particular) could generate too much information. This information could include, for example, incidental findings about paternity as well as clinical information about the child. In addition, other information may show conditions that don’t arise until adulthood. Finally, the McGill group raised concerns that screening techniques would saddle public health agencies with much larger volumes of information.
- Mark Korson, a physician who left private practice to direct the Genetic Metabolic Center for Education, warned that sequencing techniques for screening raises other questions, as the number of diseases tested for rises from 50, to 100, perhaps extending into the thousands. “For a disease like cystic fibrosis, there’s no cure, though some treatments exist. In situations where older siblings had CF, new siblings were tested early and started treatments, and had longer lives and better quality of life” he said in an interview. But for other disorders that such techniques could pick up, “what about a situation where there’s no definitive treatment? Society can save by identifying patients with rare disease which might otherwise take years and dozens of consultations before a patient is identified”. But next-generation sequencing yields genetic variants that may not be validated, or connected to a specific disease.
Another problem is coverage. In countries in and around the Arabian Peninsula, many governments have imposed premarital and newborn genetic screening. Part of the impetus for this is the high number of genetic disorders there, largely due to common practices of cousins marrying cousins. But not all countries in the region have the funds to devote to these technologies, creating gaps in coverage of inherited diseases, warned Lihadh Al-Gazali, professor in clinical genetics and pediatrics at United Arab Emirates University and Hanan Hamamy, genetic counseling specialist with Geneva University in Switzerland.
Yet another problem in the Arab world, as well as anywhere else, is education. Al-Gazali, Hamamy, and Korson warn that there aren’t enough trained experts in genetics, metabolic disorders, and screening techniques to take care of the existing screening facilities, let alone the additional burden of processing data from these new technologies (notably Korson’s Genetic Metabolic Center for Education does have programs to train and counsel practitioners and parents worldwide). “We’re not increasing the number of doctors available to treat these patients. There are maybe 100 biochemical geneticists in this country. Clinics are run by doctors with no expertise in the area. It’s compromising success.” Even in Arab countries with sophisticated equipment, Korson said he has seen the equipment but laments that there is nobody around to run it.
Golden principles of screening
Much of the discussion about newborn screens and selection of diseases goes back to a document written for the World Health Organization in 1968. Written by James Wilson, of the UK Ministry of Health, and Gunner Jungner, of Sahlgren’s Hospital in Gothenburg, Sweden, “Principles and practice of screening for disease” has been the “gold standard” for deciding which diseases to screen. As revised by WHO a few years ago, the principles read:
• The condition sought should be an important health problem
• There should be accepted treatment for patients with recognized disease
• Facilities for diagnosis and treatment should be available
• There should be a recognizable latent or early symptomatic stage
• There should be a suitable test or examination
• The test should be acceptable to the population
• The natural history of the condition…should be understood
• There should be an agreed-on policy on whom to treat
• Cost of case-finding should be economically balanced
• Case finding should be a continuous process
These steps—or their earlier incarnations, which are quite similar—may not quell every debate over screening. But they do help provide directions and a foundation for what’s apparently much needed education among practitioners as well as patients and politicians.
Andrew Porterfield is a writer, editor and communications consultant for academic institutions, companies and non-profits in the life sciences. He is based in Camarillo, California. Follow @AMPorterfield on Twitter.