Ornithine Transcarbamylase (OTC) Deficiency

Medical information you need to know as an adult with OTC deficiency

Overview of the Condition:

OTC deficiency is a rare metabolic condition in which a chemical called ornithine transcarbamylase (OTC) does not work correctly in your body. This can cause ammonia to build up in your blood over time. When ammonia builds up too much, it can cause serious health problems. You can manage OTC deficiency throughout your life with a special low-protein diet, drug therapy, and ongoing health care.

OTC deficiency is also sometimes called ornithine transcarbamylase deficiency.

In girls and women, OTC deficiency can be mild, moderate or severe. In boys and men, OTC deficiency is usually severe.

Medical Problems for Babies and Children:

  • If OTC deficiency goes undetected, babies and children may have: extreme sleepiness, irritability, vomiting, poor appetite, trouble with breathing or body temperature, unusual body movements, seizures, or coma.  These symptoms can be triggered by eating a lot of protein, or after an illness or surgery, or by steroid medication.

  • If untreated, developmental problems for babies and children with OTC deficiency can include: delayed growth, learning delays, liver damage, skin lesions, or brittle hair.

  • Newborns in some US states are now tested for OTC deficiency. If the condition is identified early and treatment and diet are followed carefully, health problems can be prevented or lessened.

  • Some babies, children and adults have a liver transplant, which prevents the build-up of ammonia.

Medical Problems for Teens and Young Adults:

  • Teens and young adults with OTC deficiency may have learning disabilities.

  • If you have an illness, fever, surgery, or are pregnant, contact your health-care provider right away.

  • Watch for signs of ammonia build-up (hyperammonemia) including: nausea, vomiting, sleepiness, or unusual problems with your mood or thinking. If you have any of these, get medical care right away.

  • Some teens and young adults with OTC deficiency have anxiety or depression. Counseling and medication can help. If you have anxiety or depression, it is important to get in touch with your health care provider to get treatment.

How to Minimize Medical Problems and Complications:

  • Follow a low-protein diet recommended by your dietician.

  • Take medicines recommended by your health care providers, which may include citrulline.

  • Avoid steroids in medication or supplements.

  • Avoid medicines that contain valproic acid, including Depakote®. Check with your doctor to find out which other medicines contain valproic acid.

  • Keep your immunizations up-to-date.

  • Stay in regular contact with your health care providers and health specialists.

  • Keep an Acute Illness Protocol that you can bring with you to the emergency room.

Fertility and Pregnancy

  • OTC deficiency does not affect your ability to have children.

  • Genetic counseling can help you and your partner understand the risks to your children. Your doctor can refer you to a genetic counselor who has a special understanding of your health issues.

  • Pregnant women with OTC deficiency must follow a careful diet with special guidance from a dietician and health care providers.  The woman with OTC also must be followed very carefully by her doctors for several weeks after the baby is born, since that is a time when she can experience sudden build-up of ammonia.

How to Get Support:

  • Get education support from teachers and specialists at your school.

  • Join a support group with people who have OTC deficiency or similar metabolic conditions. This group of health conditions is called urea cycle disorders.

  • A lot of research is being done on arginase deficiency and other urea cycle disorders. Get up-to-date information about new treatments and discoveries at the Urea Cycle Foundation website: http://nucdf.org/

Resources:

AAP/AAFP/ACP Transition Clinical Report
http://aappolicy.aappublications.org/cgi/reprint/pediatrics;128/1/182.pdf

Transition Toolkit (New England Consortium of Metabolic Programs)
https://newenglandconsortium.org/for-families/transition-toolkit/

Got Transition
http://www.gottransition.org/

National Urea Cycle Disorders Foundation
http://www.nucdf.org/

Acute Illness Protocol for OTC Deficiency
https://newenglandconsortium.org/for-professionals/acute-illness-protocols/urea-cycle-disorders/ornithine-transcarbamylase-deficiency-otc/

National Institutes of Health – Genetics Home Reference – OTC deficiency
http://ghr.nlm.nih.gov/condition/ornithine-transcarbamylase-deficiency

Genetics Referrals:

Clinical Services
http://www.ncbi.nlm.nih.gov/sites/genetests/clinic?db=genetests

Genetic Services
http://www.acmg.net/gis

What Next?

Now you can fill out the Medical Health Summary, print it, and save it. This will help you keep important medical information in one place.

This Metabolic Condition Basics guide was adapted with permission from the American College of Medical Genetics ACT Sheet