A genetic test, or “DNA test,” allows doctors to find out if you have any defective genes that may cause a urea cycle disorder (UCD).
During a genetic test, a doctor or nurse takes a sample of your DNA. This is usually done by drawing your blood or swabbing the inside of your mouth.
Then, your sample is sent to a lab where doctors look at your DNA to look for the defective gene that causes a UCD.
The results are sent back to your doctor, who will explain whether you have any defective genes that can cause a UCD and what that means for your health.
Why Genetic Testing Is Important
Some carriers of a UCD gene may not know they have it until their child is diagnosed because they may not have symptoms of a UCD themselves. Also, members of a family share some of the same genes, so if 1 member of a family learns they have a UCD, there may be others who are affected as well. If you or your child has been diagnosed with a UCD, it’s important to pay attention to other relatives, especially children, who may have similar signs and symptoms. A UCD should be considered in any person with unexplained, out-of-character behaviour that may include:
- Poor appetite
- Irritability
- Fogginess
- Low energy
- Vomiting
- Heavy or rapid breathing
- Aggressive behaviour
Some people with mild symptoms may have a UCD but not know it until it gets diagnosed later in life. They can have ammonia building up in their body to toxic levels over the years, causing permanent brain damage. If you or any family members are having these symptoms, talk to your doctor and find out who in your family should be tested for a UCD.
UCD and Genetic Testing Terms
Understand the terms you may hear related to UCDs.
Autosomal recessive disorder: A disorder that is caused by a defective gene passed down from both parents to a child.
Chromosome: The part of the cell that carries our DNA. Humans have 22 pairs of chromosomes plus 1 pair of sex chromosomes (an X chromosome and a Y chromosome for males and 2 X chromosomes for females). Chromosomes are found in the nucleus, or control center, of each cell.
Defective gene: A gene that is not working correctly.
DNA: The material that carries all the information about how a person will look and function. DNA determines things such as eye colour. Each piece of information is carried on a section of the DNA called a gene.
Gene: A small part of DNA. Genes control how our traits develop, and they pass genetic information on from parent to child.
Genetic counselor: A healthcare professional who helps explain things like the genetics of a disorder, who in a family should have genetic testing, and family planning.
Genetic disorder: An illness caused by a defective gene, which is usually inherited from the parents.
Genetic test: A test in which doctors look closely at someone’s genes to determine if he or she has any defective genes that could cause genetic disorders.
Metabolic dietitian: A healthcare professional who educates about nutrition, helps create a plan for a complete and balanced diet, and helps make any dietary changes suggested by a doctor.
Metabolic geneticist: A specialist who treats genetic disorders like UCDs.
Mutation: A change in a gene.
Neuropsychologist: A psychologist who specializes in understanding the relationship between the brain and behavior, as well as how disorders can alter behavior and brain function.
Random mutation (also called a “de novo” mutation): An alteration in the DNA caused by a change that happened when DNA was forming.
X-linked disorder: A disorder that is caused by a defective gene passed down from 1 parent to a child via the X chromosome.