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.
Figure 1: Diagram of pleiotropy. A pleiotropic gene is a single gene that controls more than one trait. Â© 2008 Nature Education All rights reserved. Today, we know that Mendel's observations were the result of pleiotropy, or the phenomenon in which a single gene contributes to multiple phenotypic traits.leiotropy should not be confused with polygenic traits, in which multiple genes converge to result in a single phenotype. In some instances of pleiotropy, the influence of the single gene may be direct. For example, if a mouse is born blind due to any number of single-gene traits (Chang et al.