Treating children with 'bubble baby disease'

An international study published in the journal Blood by researchers led by Dr. Elie Haddad, a pediatric immunologist and researcher at CHU Sainte-Justine and professor at Université de Montréal, on the topic of acute immunodeficiency (SCID).

This deficiency, known as "baby bubble disease" is a rare syndrome characterized by a total non-function of the body's immune system. The affected children have no immune response and are infected with the virus, resulting in repeated severe infections. Without appropriate treatment, in most cases this disease is fatal in the first months after birth.

SCID can be caused by mutations in various genes involved in the functioning of the immune system. The new research shows that the nature of the mutated gene (or genotype) has a significant influence on patients' survival and reconstitution of their immune system after bone marrow transplant. According to the study, the genotype must be taken into account when adapting treatment strategies to individual patients.

44 Medical Centers Involved

Funded by the U.S. National Institutes of Health, the Primary Immune Deficiency Treatment Consortium (PIDTC) involves 44 medical centers across North America. The PIDTC conducted a retrospective badysis of 662 patients with SCID who received hematopoietic stem cell transplants as their first therapy between 1982 and 2012 in 33 of these centers, forming the basis of the new study.

"Immune diseases are among the top priorities at CHU Sainte-Justine in terms of care, teaching and research," Haddad said. "Having access to such a cohort of patients with this disease and with a history of this disease is important in this area."

The results shown that survival rates of patients were higher after a transplant cell from a matched sibling donor. In this case, which represents 86 per cent of cases, the data showed that SCID genotype had a strong influence on survival and immune reconstitution. In addition, the researchers found that the age and absence of active infection at the time of transplant were also important for survival, and both were significantly badociated with improved survival following transplant.

Critical Need for Neonatal Screening

"We need to develop patient-specific treatment strategies," Haddad said. "There is a critical need for appropriate infection isolation, implement infection-prevention measures, especially before transplantation, and ensure rapid referral for bone-marrow transplant or gene therapy after diagnosis."

The study also points to the need for close monitoring of immune system reconstitution after treatment to identify patients with long-term prognosis. Further studies will be needed to identify patient- and transplant-related factors that limit early immune-system reconstitution, and to determine the most appropriate and effective interventions.

"In our future research, we will be able to badyze the effects of long-term immune-system reconstitution after hematopoietic cell transplant for this deficiency," said Haddad.