We all inherit traits from our parents through DNA, such as hair color or eye color. Our DNA carries all the information about how we will look and how our bodies will grow and work. All of that information is carried on parts of our DNA called genes. We have 2 copies of every gene: 1 from our mother and 1 from our father. When we inherit a gene that doesn’t work right, it can cause health problems like a UCD.
Urea cycle disorders (UCDs) can be passed down when one or both parents pass a copy of a gene that doesn’t work right on to their child. The most common type of UCD is called ornithine transcarbamylase deficiency or OTC deficiency. OTC deficiency is an X-linked condition. This means it is usually passed on from a mother to her child on her X chromosome. In rare cases, OTC can also be passed down from a father to his daughter.
With OTC deficiency, one parent (typically the mother) passes on the gene that doesn't work right via the X chromosome
Both parents pass on a copy of the gene that doesn't work right via any chromosome other than the X or Y chromosomes
Also called "de novo", a mutation that happened for the first time when the cells were forming, creating a gene that doesn't work right and causes a urea cycle disorder
Different genes cause different types of UCDs. There are 8 different types of UCDs, often called "subtypes":
The name of the subtype tells you which enzyme or transporter in the urea cycle doesn’t work. For example, if you have ornithine transcarbamylase deficiency, it means your ornithine transcarbamylase enzyme is missing or not working.