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.
Genetic Testing for ALS - ALS is directly hereditary in only 10 percent of families. The vast majority of ALS cases are sporadic, meaning that although there is likely a genetic predisposition involved, ALS is not directly inherited in a family. Although there is a genetic test for ALS, it is still quite limited. In 20 percent of families with inherited ALS, a change in the gene called SOD1 on chromosome 21 has been found, however, 80 percent of families with inherited ALS do not show a change in their SOD1 gene.