Serum levels of Gd-IgA1-specific IgA were elevated in IgAN patients compared with CKD controls (P<0.001) and healthy controls (P<0.001) (0.890±0.840 Units for IgAN patients, 0.482 ±0.483 Units for CKD controls and 0.419±0.289 Units for healthy controls; Figure 1C). Here, IGHA1 is linked to chronic kidney disease.