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 their association with complexes in the nucleus of the cell. Another worry with the ELISA technique is that anti-Sm antibodies have been reported in patients without SLE which would lead to over-investigating, but could be due to the quality of the antigen source used. Western blotting has a major disadvantage in that antibodies targeted against conformational epitopes can not be detected. On top of that, false positive can occur and the disease specificity is lower than other techniques. While each technique has their advantages and disadvantages, ELISA has the least severe disadvantages of potential for false positives (which are less dangerous than false negatives) and expensive.