The chemical structure of glycerol phenylbutyrate , which helps clear nitrogen from the system before it can be converted to ammonia . Children ’ s Colorado ’ s Metabolic Service used it to treat a baby born with OTC deficiency disorder and was a site in the clinical trials .
A few days later , the baby transitioned to a drug called glycerol phenylbutyrate , which accomplishes the same thing but can be taken by mouth . The Metabolic Service was involved in clinical trials for it , before it was approved by the FDA in 2013 .
Therapy continued after birth with tight monitoring from Children ’ s Colorado ’ s Level IV Neonatal Intensive Care Unit , and the baby has been there since . The NICU and Metabolic teams check his blood ammonia constantly and adjust medications and the precise amount of protein in his diet to maximize growth and minimize ammonia production . He ’ s now three months old and awaiting a liver transplant .
“ We keep an eagle eye on him ,” Dr . McCandless says . “ If there ’ s even a hint his ammonia levels are rising we treat it aggressively . Every time this baby is fussy he gets his ammonia checked .”
The good news is that the transplanted liver will contain the enzyme needed to convert ammonia . It will essentially be curative .
The transplant team was consulted soon after birth , and the baby was listed for transplant as soon as the team felt it could safely be done . He ’ s currently listed .
“ It ’ s really unusual for boys with severe OTC deficiency to survive ,” he says . “ And those who do have really bad brain injury . We expect this boy to grow up free of injury from high ammonia .”
Better yet , it ’ s possible that one day soon a transplant may no longer be necessary . Dr . McCandless ’ s team is currently involved in clinical trials for the first gene therapy for the condition . •
SHAWN MCCANDLESS , MD
Chair , Genetics and Inherited Metabolic Diseases , Children ’ s Hospital Colorado
Professor , Pediatrics-Clinical Genetics and Metabolism , University of Colorado School of Medicine
Feb 2021 - present Constant monitoring of ammonia levels
Feb 2021 : Treatment with oral glycerol phenylbutyrate begins days later
May 2021 : Baby is listed for transplant
9