**REPOST**
Our Carrier Connections program features a different X-linked condition each month with the goal to increase awareness of X-linked conditions and how they impact the lives of women and girls.
This month, we are featuring ornithine transcarbamylase (OTC) deficiency is an X-linked genetic disorder marked by a complete or partial lack of the enzyme ornithine transcarbamylase. This enzyme is critical to the urea cycle as it is tasked with converting ammonia, a byproduct from the breakdown of excess protein subunits in the body, to urea so that the body can excrete it through the urine. In individuals with OTC deficiency, this enzyme does not function properly, resulting in the accumulation of ammonia in the bloodstream. The presence of excess ammonia in the blood causes complications in the nervous system, resulting in a range of severe to mild symptoms. OTC deficiency can become evident at any age, but has the most extreme effects when it occurs in infants.
Symptoms in females are widely variable, with some individuals showcasing more severe clinical manifestations than others, and some not having any reported symptoms.
For example, while some females only report chronic headaches following protein consumption, other individuals have been found to experience acute liver failure, hyperammonemia, and other symptoms typically seen in affected males. Additionally, some females report worsening symptoms during pregnancy and require close monitoring of protein levels by a medical team to ensure a safe delivery. Even so, females are at a heightened risk of hyperammonemic crisis during pregnancy and should consult their physician before getting pregnant.
OTC deficiency is an X-linked genetic disorder marked by a complete or partial lack of the enzyme ornithine transcarbamylase. This results in the accumulation of ammonia in the bloodstream and causes complications in the nervous system, resulting in a range of severe to mild symptoms. Approximately 20% of OTC females experience symptoms. Some females do not express excess ammonia levels until pregnancy. Females who do develop symptoms in childhood often experience headaches after protein ingestion. A study determined that girls with OTC deficiency may exhibit episodes of hyperammonemic encephalopathy, or ammonia buildup in the brain, and cognitive decline.
Today, we are joined by Andrea Gropman, M.D., FAAP, FACMG, FANA. Dr. Gropman is the Director of Neurometabolic Translational Research Center for Experimental Neurotherapeutics St. Jude Children's Research Hospital. She is also is the principal investigator of the Urea Cycle Disorders Consortium (UCDC) and the UCDC imaging consortium and the deputy clinical director of the Mito EpiGen Program. Her research interest focuses on establishing biomarkers of neurological injury in patients with inborn errors of metabolism, such as urea cycle disorders and mitochondrial disorders, using specialized neuroimaging modalities and cell markers.
Carrier Connections is sponsored by Kyowa Kirin and Amgen. For more information about our organization, check out rememberthegirls.org.
OTC resources:
