Figure 2. IFs and human disease.
The involvement of IFs with human disease occurs at several levels. First, mutations in genes encoding IF proteins may either precipitate or predispose to a wide range of human diseases. It is also possible that natural selection has favored unique variants that may serve a protective role (16), although this hypothesis remains to be tested. Second, IF proteins, as a group, are essential for the formation of a variety of cell-specific inclusions that represent hallmarks of various diseases. Formation of these inclusions is generally independent of the presence of an IF mutation but does occur in the context of GFAP mutation in Alexander disease (18). Third, antibodies specific for IF proteins are routinely used in pathology laboratories across the world to help identify the origin of poorly differentiated tumors and are beginning to be used to assess tissue injury (directly in tissues, in blood, or in cerebrospinal fluid [CSF]) (16, 18). In addition, antibodies specific for IF proteins have been observed in the context of some autoimmune disease (16). ALS, amyotrophic lateral sclerosis; NIFID, neuronal IF inclusion disease.