Étienne has a rare, life threatening genetic condition called Severe Combined Immune Deficiency, which affects an estimated 1 in 100,000. “Combined” because both T-cells, which are critical to fighting viruses and co-ordinating attacks, and B-cells, which are critical to making antibodies, are non-existent or do not function. Étienne’s form of SCID is ADA Deficiency. He lacks the blueprint to produce a “housekeeping” enzyme (ADA) without which there is a buildup of toxic metabolites in his body. As a result, he cannot produce T, B, and NK cells. Children with ADA-SCID are also low on neutrophils, another important white blood cell that kills bacteria and fungi.
Children with ADA-SCID often die within the first year of life without treatment due to infections that they do not have tools to fight, even with the help of antibiotics or other treatments. It is a horrible disease that is still taking the lives of children. It is senseless and heartbreaking.
Newborn screening can greatly improve the odds. Ontario became the first and only province in Canada to add SCID to its newborn screening in August 2013. Étienne, born in June 2014, became the second baby to be diagnosed through this newborn screening.
With ADA-SCID, there is the treatment option of enzyme injections called Adagen. These injections cost nearly $10,000 per week. It does not lead to a complete immune reconstitution. Eventually, the body develops an immune response to the ‘peg’, the vehicle for the enzyme. A bone marrow transplant is the only long term treatment option. Ideally, there would be a sibling match (survival rate = 80%). Étienne is an only child. There is the option of an unrelated match (survival rate = 50-60%).
With an unrelated match (vs sibling match), there needs to be a chemotherapy regimen. Some forms of SCID, such as ADA-SCID, are more sensitive to chemo than others, so children frequently suffer organ damage and failure as a result.
There is also the option of gene therapy done in clinical trials in the US, UK and Italy. Gene therapy for ADA-SCID is not available in Canada. The protocols differ, but the basic idea is that the patient is their own bone marrow donor. In the lab, a normal copy of the ADA gene is transferred into their stem cells using a modified virus that acts a vector, so that they can produce the missing enzyme on their own. The first ever human recipient of gene therapy was a young girl with ADA-SCID in 1990. She is alive today thanks to gene therapy. Within the last decade, Italian researchers figured out a way for it to be successful. There have been over 40 children worldwide who have T-cell reconstitution and do not need Adagen because of gene therapy. Some of the risks of gene therapy are unknown and unquantifiable, but there have not been any serious consequences in the trials so far. The current trials are using a lentivirus because it is thought to be safer (that is, less likely to cause cancer) and just as effective as the retrovirus they’ve used in previous trials.
Gene therapy is the only long term option for Étienne. There are no bone marrow matches for him in the donor registry. It’s more difficult to find matches for him because of his ethnic diversity. He is enrolled in a clinical trial at UCLA, and his transplant surgery will take place in April.
The medical side is very very serious, but it is not the whole story. Étienne is an awesome little person, and we have a lot of joy in our lives. He is playful and enjoys exploring his environment. His favourite toys are his hands, feet, voice, a pot holder, and some wooden bowls. He is desperately trying to crawl. We are going to be introducing foods to him very soon! Since we have had him in June, we have been having a blast with him. We feel so lucky to have such a fun, strong, playful, and adorable baby.
More information about Étienne: Ottawa Sun – CHEO test helps diagnose rare genetic contidion
News on gene therapy for ADA-SCID: Yahoo News – UCLA Researchers Announce Gene Therapy Cure for 18 ‘Bubble Baby’ Patients
With the help of our social worker at the hospital, we are trying to tap into all available resources, however it will not be enough to cover all costs related to the surgery and lengthy recovery period while we are both unable to return to work.
You can help us by donating toward the costs of Étienne’s surgery and recovery. Every amount helps.