However, based on the number who had an endoscopy following a Cytosponge-TFF3 procedure but did not have Barrett's oesophagus or cancer (n=90), and on the number who successfully swallowed the Cytosponge-TFF3 but did not have Barrett's oesophagus or cancer (n=1523), we estimated the specificity of the Cytosponge-TFF3 procedure to detect Barrett's oesophagus, dysplasia or cancer to be 94%. The gene discussed is TFF3; the disease is dysplasia.