John Sincavage, MD

Alexander M. White, III Memorial Postdoctoral Research Fellowship Award
$25,000 over one year

Children's Hospital of Philadelphia Center for Fetal Research

In Utero Epigenetic Editing in a Humanized Mouse Model of Hereditary Tyrosinemia Type 1: Building a Therapeutic Paradigm for Congenital Metabolic Liver Disease
Mentor: William Peranteau, MD

Hereditary tyrosinemia type 1 (HT1) is a congenital disease of liver metabolism caused by a defective enzyme, fumarylacetoacetate hydrolase (FAH), in the tyrosine metabolism pathway that allows toxic substances to accumulate. Like other diseases of liver metabolism, the condition is progressive and can be lethal in the first months of life. Survivors are at risk for cirrhosis and liver cancer in early childhood. Liver transplant is the only definitive cure for HT1, and with other metabolic liver diseases represents the second most common reason for liver transplant in children. Management with twice daily nitisinone supplementation prevents disease progression by blocking an enzyme, hydroxyphenylpyruvate dioxygenase (HPD), upstream of the disease-causing FAH enzyme, preventing the formation of toxins and shunting metabolites elsewhere. However, this must be initiated immediately at birth along with a strict, specialized diet to prevent irreversible organ damage. Resistance to nitisinone therapy sometimes develops, and lifelong adherence is difficult to maintain. Gene therapy, and specifically gene editing, has shown remarkable promise in delivering durable therapy for inborn errors of metabolism. The proposed research will attempt to use new CRISPR-Cas9 gene editing technology to silence the HPD gene without changing the DNA code, known as epigenetic editing. We plan not only to demonstrate that targeted epigenetic reprogramming can silence the HPD gene to cure HT1, but to do so before birth prior to irreversible organ dysfunction with a reliable in utero delivery strategy that specifically targets the liver. We hope to (1) demonstrate epigenetic editing as a versatile and viable strategy for treating congenital metabolic liver disease and (2) reinforce that these diseases are best treated by targeting the liver during fetal development.