Parents pass these diseases down to their children through defective genes. We all inherit two copies of our genes, one from each parent. With most UCDs, you must get a defective gene from both parents to get the disease. The genes tell your child’s body how to break down protein.
One UCD, called ornithine transcarbamylase (OTC) deficiency, is what doctors call a sex-linked disorder. Mothers carry the gene on their X chromosome, and they mostly pass it to their sons.
Symptoms
UCDs fall into two groups:
Complete UCD: This means your baby has a severe or total lack of the enzyme. You’ll notice symptoms in the first couple of days:
Feeding them supplements of sugars, fats, and amino acids
Medicines to remove extra nitrogen
Long-term treatment can manage UCD symptoms. Your child will need frequent blood tests throughout their life to check ammonia levels. Stresses on their body -- like illness, injury, or surgery -- can cause their levels to rise. During those times, you’ll need to give them extra calories so their body has plenty of fuel.
A liver transplant can reverse the symptoms of a urea cycle disorder
Diagnosis
Most newborns in the U.S. are tested for ASS1 and ASL, but how well the tests work is different in each state. Many states test for arginase and citrin deficiencies. A handful also test for OTC and CPS1 deficiencies.
If your baby starts to show symptoms after you get home, the doctor will do a physical exam. They’ll ask about your family history and do tests. They’ll look for ammonia in your child’s blood and amino acid in their blood and urine. The doctor can take a tiny piece of their liver through a process called biopsy. They’ll test it for enzymes. Genetic tests will usually confirm the diagnosis.