OTC basics

OTC Deficiency: An Introduction

This page provides educational information about OTC deficiency, including how it develops, common symptoms, and why family history matters.
The video below offers a brief overview intended to support understanding and awareness.

What is OTC Deficiency?

Ornithine transcarbamylase (OTC) deficiency is a rare genetic condition that affects the body’s ability to remove ammonia, a natural waste product created when we break down protein. When the OTC enzyme doesn’t work properly, ammonia can build up to dangerous levels, leading to symptoms such as vomiting, confusion, extreme sleepiness, or even seizures. OTC deficiency can appear at any age.

Some people - especially newborn males - show symptoms early in life, while others may not experience issues until childhood or adulthood. Illness, stress, fasting, or high protein intake can trigger symptoms. Although serious, early awareness and proper testing can make a meaningful difference for individuals and families.

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What You Need
to Know

How OTC Deficiency Develops

OTC deficiency is caused by a genetic change passed down through families. Because the gene is located on the X chromosome, symptoms often appear more strongly in males—but females can be affected as well. Since the condition can be silent for generations, understanding your family history is an important part of recognizing risk.

Recognizing the Signs and Symptoms

Symptoms can range from vomiting, headaches, and confusion to more serious complications like seizures or coma. These signs may appear suddenly and escalate quickly, especially during illness, fasting, high-protein intake, or physical stress. Because episodes can strike without warning, recognizing early symptoms and acting promptly is essential.

Living with and Managing OTC Deficiency

Managing OTC deficiency is a lifelong process, but with the right plan many individuals live safely and well. Treatment may include controlled protein intake, medications that help remove ammonia, and regular care from metabolic specialists. Because episodes can recur, it’s important to stay alert to symptoms - especially during illness, fasting, stress, or high-protein intake.