What is Citrullinemia? (a urea cycle disorder) and some answers to frequently asked questions.


(sĭt’rə-lə-nē’mē-ə, sĭ-trŭl’ə-)

Citrullinemia is an inherited disorder that causes ammonia and other toxic substances to accumulate in the blood. Two forms of citrullinemia have been described; they have different signs and symptoms and are caused by mutations in different genes.

Type I citrullinemia, which is what Corrigan has,  (also known as classic citrullinemia) usually becomes evident in the first few days of life. Affected infants typically appear normal at birth, but as ammonia builds up in the body they experience a progressive lack of energy (lethargy), poor feeding, vomiting, seizures, and loss of consciousness. These medical problems are life-threatening in many cases

Type I citrullinemia is the most common form of the disorder, affecting about 1 in 57,000 people worldwide. Type II citrullinemia is found primarily in the Japanese population, where it occurs in an estimated 1 in 100,000 to 230,000 individuals. Type II also has been reported in other populations, including people from East Asia and the Middle East.

Citrullinemia belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of chemical reactions that takes place in liver cells. These reactions process excess nitrogen that is generated when protein is used by the body. The excess nitrogen is used to make a compound called urea, which is excreted in urine.

Mutations in the ASS1 gene cause type I citrullinemia. This gene provides instructions for making an enzyme, argininosuccinate synthetase 1, that is responsible for one step of the urea cycle. Mutations in the ASS1 gene reduce the activity of the enzyme, which disrupts the urea cycle and prevents the body from processing nitrogen effectively. Excess nitrogen (in the form of ammonia) and other byproducts of the urea cycle accumulate in the bloodstream. Ammonia is particularly toxic to the nervous system, which helps explain the neurologic symptoms (such as lethargy, seizures, and ataxia) that are often seen in type I citrullinemia.

For more detailed information about Corrigan and his specifics please visit the following links: Rare Disease Day 2010

For information about Corrigan’s highest ammonia please go here

“How Corrigan’s story began”

Corrigan’s first year-broken down by the numbers

Are you considering a port to make blood draws easier? Here is our experience and a follow up post here so you can see how the scar has healed.

Are you considering a g-tube for your UCD child? you can check out some of our posts here, here and also here.  It was not an easy decision but it was a great one, if you’d like to read about my concerns you can do so here, here and here.

For more information on all Urea Cycle Disorders please visit the National Urea Cycle Disorders Foundation at NUCDF.org


All posts, on Mooney=MC2,  that include information about the medical care/treatment of Corrigan’s Citrullinemia are for personal documentation and in no way are to be taken as “medical advice.”  All genetics teams have their own approaches to the management of Urea Cycle Disorders and just because our team does something a certain way does not mean that YOUR child’s team is doing it wrong.  All management plans are customized to each child’s needs/disorder and Corrigan’s information is exclusive to his very specific needs and are overseen carefully by his team at Johns Hopkins Hospital.

If you have any questions about anything you read  here, in regards to UCD’s, please feel free to take what you have read directly to your own team.  Remember, I am just a mom, not a doctor…your child’s doctors are the best people to contact with specific medical questions…however, I would LOVE to talk to you about “everyday living” with Urea Cycle Disorders and would be happy to answer any questions regarding Corrigan…anytime at all.


8 thoughts on “What is Citrullinemia? (a urea cycle disorder) and some answers to frequently asked questions.

  1. As u know Alysa has ASA Lyase, at 17 days old she was misdiagnosed with citrullenemia! She has been doing well up until she was 10 now we have had nothing but problems! Hope it all gets better soon for all these special children!


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  3. I have to express thanks to you for rescuing me from this type of condition. After exploring throughout the world wide web and obtaining techniques which are not helpful, I assumed my entire life was over. Being alive without the answers to the difficulties you have resolved by way of your posting is a serious case, and the kind which might have negatively affected my entire career if I hadn’t discovered your web blog. Your own personal expertise and kindness in playing with all the stuff was crucial. I don’t know what I would have done if I had not encountered such a stuff like this. It’s possible to at this moment look ahead to my future. Thanks for your time very much for this expert and results-oriented guide. I won’t be reluctant to recommend your web sites to anyone who would need recommendations on this situation.


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  5. My Daughter is turning 7 this month and also has Citrullinemia… Its nice to see other people and not feel so alone with the disorder…I love the sign! Its super cute what a great picture!!


    • Hi Kelly! Awesome of you to stop by and leave comments! So your daughter is 7 then you have TONS of experience to share! How is she doing? Are you a member of any UCD Facebook groups? Or the REACH Group through the NUCDF? There’s so much more support out there I can hook you up with if you’d like! You can also email me anytime, I’d love to learn more about your sweet girl! I am using mindy.mooney@gmail.com mostly these days if you ever want to talk!


  6. Yea my name is denisha jade ricketts yea I got citruilliamia type 1 I started to bring up milk when I was a baby no one knew wat was wrong with me and my sisters it took the doctors more dan ; months to know wat it was yea I lost my two sisters I got my own kids I was in hospital for whloe nine months beacause how the citruillamia made me feel high ammonia levels I just don’t know it real hard livening with citruliiamaia not nice


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