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.
C9ORF72. This gene, discovered in 2011, is the most common genetic cause of ALS. (Its name refers to the position of an âopen reading frameâ on chromosome 9). Mutations in this gene account for between 25% and 40% of all familial ALS cases (depending on the population), and also approximately 4% to 6% of sporadic cases.As noted above, these apparently sporadic cases are in fact genetic.utations in SOD1 were first described in 1993, and SOD1 was the first gene known for ALS. It accounts for about 10% of familial ALS, or 1.5% to 2% of all ALS. It is inherited in a dominant manner. How SOD1 mutations cause ALS is unknown.