Newborn screening for "bubble-baby" disease boosts survival of children

Screening newborns for severe combined immunodeficiency disease (SCID) significantly increases the survival of children after bone marrow transplantation, a new North American study finds.

Published today in The Lancet with an accompanying editorial, the retrospective study was co-led by Elie Haddad, an Université de Montréal medical professor and clinician scientist, pediatrician and immunologist at the UdeM-affiliated CHU Sainte-Justine mother-and-child hospital.

The research shows that the gradual adoption of newborn screening for SCID since 2008 in North America has boosted the survival rate from 73 per cent between 1982 and 2009 to 87 per cent between 2010 and 2018.

The survival rate jumped to 92.5 per cent in children whose SCID was detected and treated at birth, whereas it was much lower in children diagnosed after the onset of symptoms. Furthermore, the proportion of babies transplanted and who never contracted an infection was significantly higher, an aspect that played a major role in increasing their survival.

Also known as "bubble-baby" disease, SCID causes major immune cell dysfunction and affects 40 to 80 children annually in North America. Children with SCID appear perfectly healthy at birth but are extremely susceptible to infection. The disease is fatal (usually within the first year of life) unless the child receives treatment, such as a bone marrow transplant, gene therapy or enzyme therapy.

"The improvement in post-transplant survival is staggering and alone justifies the implementation of a newborn screening test for SCID and other life-threatening diseases of the immune system," said Haddad, who is also the recipient of the BMO Chair in Pediatric Immunology and the head of the Immuno-allergy and Rheumatology division at CHU Sainte-Justine. "This study highlights the importance of prevention and of collaboration in precision health."

Several studies had suggested that systematic neonatal screening for SCID could improve the survival rate of affected children, but the data were inconclusive. Done in collaboration with numerous research centres in Canada and the U.S., Haddad's shows that the increase in the survival rate of children with transplants coincides with the rollout of a screening test in various North American regions begun in 2008. Since 2018, all U.S. states have been conducting preventive screening for SCID. In Canada, seven provinces and territories have followed suit; in Quebec, the process is underway.

The continuing adoption of newborn screening has made it possible to detect the disease earlier before symptoms appear, and to take all possible steps to prevent infection and quickly provide treatment. Previous research already showed that being younger than 3.5 months at the time of transplant and the absence of infection significantly improved survival rates.

Given that we are preventing children from dying and from undergoing much more difficult treatments with subsequent consequences, these results will encourage other countries around the world to adopt newborn screening for SCID and other life-threatening immune diseases that the test can detect."

Elie Haddad, Professor, Université de Montréal