Richard Poulin, father of a young girl with aromatic L-amino acid decarboxylase (AADC) deficiency, discusses his daughter’s positive experience with an investigational gene therapy.

AADC deficiency is a rare genetic disorder that affects the nervous and musculoskeletal systems of young patients. It is caused by a defect in the dopa decarboxylase (DDC) gene, which leads to a reduction in the critical neurotransmitters dopamine, norepinephrine, epinephrine, and melatonin in the brain. 

Mr. Poulin’s daughter, Rylae, received an investigational gene therapy from PTC Therapeutics when she was just under 2 years old. According to him the difference between her before and after the surgery was “day and night.” Mr. Poulin notes that on top of the gene therapy, he and his wife began speech therapy, physical therapy, occupational therapy, and sensory integration early on as they believe in the importance of early education and early intervention. One month after receiving the gene therapy, Rylae was able to sit up by herself, and recently, her teacher claimed that Rylae would likely grow up to be a normal child. Rylae, who is now almost 4, is able to ride a horse, swim, run on the playground, form short sentences, giggle, and have sleepovers.

Mr. Poulin notes that the only concerns he has about gene therapy is the lack of accessibility to it, especially early on. He considers himself lucky for Rylae to have received it when she did as he learned that many parents wait years for gene therapy even when they are enrolled in a clinical trial. However, due to the important brain development occurring in the first few years of life, making gene therapy accessible to parents early in their child’s life is critical for the child’s success.

For more information about AADC deficiency, visit and our AADC deficiency Panel Discussion.