measure anti-ENAs and ways to improve this testing and reporting. Double immunodiffusion (DID) and counterimmunoelectrophoresis (CIEP), two forms of gel-based techniques, are used to gain information on the clinical significance and the role of these antibodies in those with CTDs. Techniques Gel-based Since the discovery of ENAs, they have been used as a diagnostic tool in connective tissue disease. Two widely used gel-based techniques were used to identify anti-ENAs and their associations to disease in early work, double immunodiffusion (DID) and counterimmunoelectrophoresis (CIEP). Both of these techniques require the precipitation of antigens for valid results. Depending on the anit-ENA being investigated, one technique may be used over the other. For example, Scl-70 antigen is less negatively charged, which can result in the antigen traveling in the same direction as the antibody. This would result in the antibody-antigen complex not precipitating; leading to invalid results. In addition, some anti-SS-B antibodies commonly identified in Sjögren syndrome may not be detected with this method. However, this method is economically feasible and specific to confirm a diagnosis. There are two sensitivities to note when viewing data from these gel-based techniques, assay sensitivity and disease sensitivity. Assay sensitivity is the ability to recognize when an antibody is present, while disease sensitivity is the ability to recognize the frequency in which the antibody occurs in a disease. Due to limitations of gel-based techniques in disease sensitivity, other techniques have been explored in order to increase assay sensitivity without decreasing disease sensitivity. For example, in patients with Systemic lupus erythematous (SLE), only 8–40% have detectable anti-SM when using gel-based assays. CIEP has been shown to be more sensitive than DID. Hemagglutination, ELISA, Western Blot Three additional techniques, passive hemagglutination, enzyme linked immunosorbent assay (ELISA), and western blotting (WB), can be used in order to identify ENAs and link them to specific diseases. Passive hemagglutination was popular in the late 1970s, but very few studies have been done using them and was restricted to anti-Sm and anti-ribonuclear protein (RNP) antibodies. Enzyme linked immunosorbent assay (ELISA) has become the most widely used technique for testing for anti-ENAs due to them being simple to perform, quantitative, and high volume output. While this method has increased assay sensitivity and is efficient for high volume labs, they have a much lower disease specificity than alternative techniques. This is due to the inability to properly isolate the ENAs without large costs due to