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.
Further evidence for common descent comes from genetic detritus such as pseudogenes, regions of DNA that are orthologous to a gene in a related organism, but are no longer active and appear to be undergoing a steady process of degeneration from cumulative mutations.