OTC FAQs

If an individual has OTC, they are born with it. When symptoms start is variable.

Significant illness, long periods of fasting, possible very high protein intake, oral and IV steroids.

Typically pretty soon in the process. Though if ammonia levels are elevated, often times loved ones around then notice before the individual.

See our OTC Fact Sheet

A medical alert bracelet would be helpful to notify emergency personnel.

Research has focused mostly on drug therapies for the condition. However, research regarding RNA and gene therapies are being done on other conditions and could be utilized in the future for OTC deficiency.

In general it depends where you are looking. We've found that peer reviewed journal articles are always the best resource.

The family gene mutation is located on the OTC gene. Mutations on this gene affect/reduce the activity of the OTC enzyme which causes the disease.

The mutation is called c.-106C>A. It is located in the promoter region of the gene, meaning it is like a light switch that helps to activate the gene. So at position -106, where there should have been a cytosine, there is an adenine. This shift is like a spelling mistake which causes the DNA to not provide the correct instructions to make the enzyme work as it should.

It is associated with a late onset variant of the condition which is less common then the classic form of OTC deficiency.

We all have changes in our genes that occur as we are developing. The very first person affected in the family had this change occur spontaneously. There was nothing that could have prevented it or anything that the individual could have done differently. Once that individual was affected, it was then passed in the family.

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No, this requires a more specific look at the family mutation than the 23 and me kit does.

With the late onset variant, it is possible to be affected and not had symptoms. Especially if you have never received steroids or had a significant illness.

Yes, there is no urine test for DNA studies.

The blood test looks at the specific gene that causes the condition to see if it has a mutation which would cause the disease.

Probably, this gene change was just found this year after several years and studies over the last couple of decades.

As soon as possible, especially for males.

If you don’t have the mutation, you do not need to be retested. However, if you are positive and are seen in the clinic, it depends on initial labs and treatments needed.

Yes, this can be provided by the local genetics clinic and is typically given at the first clinic appointment and placed in the electronic medical record. You can find more about OTC ER & Treatment Letters here >>

This depends on how high and for how long ammonia levels are elevated. A short and small increase of ammonia will have a very short recovery time. A very high ammonia, especially one that was high for a long period of time, can take much longer to recover from.

If needed, medications in this condition are ammonia scavengers (buphenyl and ravicti), citrulline to continue the urea cycle, and possibly other supplements depending on diet and labs.

Ammonia scavengers grab on to excess ammonia to reduce levels, citrulline helps to continue the urea cycle on past the metabolic block and also helps a little to reduce ammonia.

Typically, your labs will indicate whether medication would be helpful to you or not.

Your local genetics clinic.

Not necessarily, especially depending on gender.

No, testing and a visit with the metabolic clinic is necessary to determine your specific treatment plan.

I wouldn’t expect that your daily life would change. We do recommend avoiding steroids. Treatment differs on gender and the situation. See fact sheet.

Yes. Avoid oral and IV steroids. During illness, avoid fasting. Focus on getting enough liquid and calories to prevent your body from breaking down its own protein (muscle) which causes an increase in ammonia. If you’re unable to keep down foods and liquids, then seek help at an emergency room with your protocol to receive IV fluids with sugar to provide calories.

Avoiding dehydration and long periods of fasting are recommended. Unless one is doing extreme exercise there should not be concern about exercise. In general, a well-balanced diet is recommended unless you have been instructed otherwise by your genetics clinic or metabolic dietitian.

No, in fact- not enough protein is not good for the body with OTC either.

If a child has had frequently elevated ammonia levels, developmental delays can be seen.

Typically pregnancy goes okay, however delivery can be difficult because of the stress placed on the body. With late onset OTC, there may be no issues, though monitoring in the postpartum period of any concerns could be warranted.