A U wave as seen on ECG. An electrocardiogram of an 18-year-old man showing U waves, most evident in lead V3. The U wave is a wave on an electrocardiogram that is not always seen. It is typically small, and, by definition, follows the T wave. U waves are thought to represent repolarization of the papillary muscles or Purkinje fibers.
HCP is caused by mutations in the CPOX gene, which codes for the enzyme coproporphyrinogen oxidase. This enzyme is responsible for the sixth step in the heme biosynthetic pathway, converting coproporphyrinogen III to protoporphyrinogen IX.
What causes TTR-FAP? Family genetics are the main cause of TTR-FAP. This means that there is a chance that the mutated gene that causes the disease can be inherited from one or both of your biological parents. And, if you carry the genetic mutation, there is a chance that you can pass it on to your children.