ST8SIA4 and cystic fibrosis: Furthermore, expression of genes involved in glycosylation of mucins and sialic acid metabolisms, namely sialyltransferase ST8SIA4, ST6GALNAC2, mannosidase MAN1A1, and acetylglucosaminyltransferase B3GNT8, was also validated as unique to CF (Figure 6).