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.
About 50% of patients presenting with a first idiopathic venous thrombosis have an underlying thrombophilia. Thrombophilias are hereditary conditions that are risk factors for venous thrombosis (see Table 1). Lupus anticoagulants are acquired risk factors for venous as well as arterial thrombosis.Several thrombophilic conditions have been reviewed in other Medscape Reference articles.upus anticoagulants and antiphospholipid syndromes are present in 4-14% of the population. Table 1 shows the incidence of hereditary hypercoagulable disorders in the general population and the risk for thrombosis and recurrent thrombosis.