A Better Start to Life

Infants with Prader-Willi, Angelman, and Dup15q syndromes exhibit varying degrees of behavioral problems, intellectual disability, autism, seizures, and obesity. In Australia, infants are not screened for these rare disorders as part of the standard newborn screening program – leaving many undiagnosed during the first years of life.

“Tests are currently only performed on those suspected of having these disorders – and only if features are recognized by a child’s doctor and subsequently referred for appropriate testing,” said David E. Godler, first author of a new study into testing for the disorders (1). “This is not the case with newborn screening, where testing is performed on all newborns before symptoms become apparent.”

To address this need, researchers developed a cost-effective test that can simultaneously screen for all three disorders in newborns and be scaled to the population level (2). The test evaluates the methylation levels of the SNRPN gene to distinguish between children with the disorders – who exhibit high methylation levels – and those without. The test yielded high sensitivities (99 percent for Prader-Willi, 93.8 percent for Angelman, and 77.8 percent for Dup15q syndrome), 100 percent specificity, and high positive and negative predictive values.

“Having a high positive predictive value is important for newborn screening because it ensures that there is a lower number of false positive results that need to be repeated, leading to lower overall laboratory costs, less work for maternity services in obtaining a repeated blood sample, and minimizes the psychological effect on families,” said Godler (1). Ultimately, their findings show that it is possible to use SNRPN methylation analysis to screen for all chromosome 15 imprinting.

Godler highlighted the benefits that this type of test could bring for newborns with each disorder. “For Prader Willi, diagnosis in infancy allows for early initiation of growth hormone treatment to improve long-term health outcomes,” he said. “For Angelman and Dup15q, most infants do not receive an early diagnosis that would allow intervention in the first year of life. But such early diagnosis, if available through newborn screening, could prevent the diagnostic odyssey and reduce medical costs and the significant stress and anxiety currently experienced by the families while they await a diagnosis (1).”