Genome screening for newborns on the rise
Genetic tests can identify a risk of genetic diseases as early as infancy. A research team has analysed the genetic material of thousands of babies - and may have saved the lives of some of them. But many questions remain unanswered.
Genome sequencing can be used to identify children who are likely to develop a certain genetic disease. A DNA sample can provide information about hundreds of impending diseases, which is far more than the standard newborn screening tests used to date. Genome screening could complement existing standard tests and improve healthcare. This is the conclusion reached by a US research team of around 50 people who have published the initial results of a study of 4,000 infants veröffentlicht hat.
The underlying Project GUARDIAN is one of the first in the world to advance the sequencing of genetic material in newborns on a large scale. In the near future, up to 100,000 infants are to be tested for risks of serious diseases that often break out in the first few years of life. "This will allow us to take preventive action not just in a few, but in a significant number of children," hopes paediatrician Joshua Milner from Columbia University, one of the study authors. The aim is to treat early. Otherwise, the window of opportunity for the best treatment for the disease may already be closed, says his colleague Wendy Chung, who initiated the study in New York. According to Milner, we are on the brink of a revolution in paediatric medicine.
Newborn genomic screening will inevitably gain in importance, not just in the USA and Europe, but worldwide.
"Genomic newborn screening will inevitably gain in importance, not only in the USA and Europe, but worldwide," confirms paediatrician Heiko Brennenstuhl from the Institute of Human Genetics at Heidelberg University Hospital. He heads the "Genomic Newborn Screening" working group there and was not involved in the study. Molecular genetic methods are already used in regular newborn screening for individual diseases in many countries, including Germany. In Switzerland, genetic tests are subject to the Federal Act on Human Genetic Testing.
The focus of genome screening in the USA was on 156 rare but treatable diseases that are highly likely to develop if a corresponding gene variant is present. More than 70 per cent of the parents approached who came to the New York hospital to give birth took up the free offer. Of these, 90 per cent also agreed to the search for around 100 other gene variants that lead to neuronal developmental disorders. The latter are not really treatable, let alone curable. However, the authors argue that the epileptic seizures associated with such disorders could perhaps be better controlled through early intervention.
The German Genetic Diagnostics Act requires that screening is only carried out for diseases that are preventable or treatable according to the generally recognised state of science and technology or that can be addressed preventively, explains Brennenstuhl. "However, what is considered treatable is not defined. This leaves room for interpretation," he says. The inclusion of incurable diseases in screening tests is considered questionable at the Heidelberg Institute of Human Genetics: "If there are no immediate health benefits, screening should be critically scrutinised."
Life-saving measures
Among the first 4,000 newborns, the experts from Columbia University identified 120 babies at risk, of which the standard US screening with biomarkers for around 60 diseases only detected 10. Most of them, 92 children in total, suffered from genetic mutations that cause a dangerous deficiency of an enzyme (G6PD), while others suffered from mutations that lead to short stature. One infant was found to have a rare gene variant that causes a severe immunodeficiency. This meant that a presumably life-saving bone marrow transplant could be carried out at an early stage.
These are impressive examples, but genetic screening also has its pitfalls. For example, 25 pairs of parents initially received a false positive result for their child, meaning that the poor prognosis subsequently turned out to be a mistake. According to human geneticist Jonathan S. Berg from the University of North Carolina, many questions remain unanswered, as he explains in the Editorial Team of this issue. It is not always easy to distinguish between "benign" gene variants that are unlikely to lead to the disease and those that are most likely to result in an outbreak, especially - due to a lack of data - in people of non-Eurasian, i.e. African, descent.
At the time of the examination, most babies cannot yet be diagnosed with a clinical disease. "It remains difficult to predict how a genetic condition will manifest itself as a disease in a person," writes Berg. There is often a residual uncertainty as to whether a child will benefit from private pension provisions that may be costly or burdensome. Brennenstuhl also believes that genomic newborn screening still requires a great deal of research: "The key challenge here is not technical feasibility, but creating a system that is both medically sustainable and ethically well thought-out and socially just."
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