ICONE study (IgA Complement and NEphropathy is a prospective monocentric observational study.

The main objective is to evaluate the relevance of complement activation as a biomarker of disease severity and progression in patients with a biopsy proven IgAN.

IgA nephropathy (IgAN) is a common cause of glomerulonephritis and a major cause of end stage renal disease in up to 20-40% of patients. However, its prognosis still cannot be accurately predicted due to the high heterogenicity of clinical presentations and courses. Complement dysregulation is a main driver of glomerular damages in many glomerulonephritis. Given the growing body of evidence of complement lectin/alternative pathways activation in IgAN pathogenesis, the investigators propose the evaluation of a combination of biomarkers of infra-clinical complement activation to stratify the risk of disease's progression. This study aims to identify subsets of patients in whom complement activation plays a critical role in disease progression. This is of particular interest in the aera of emergence of complement-targeting therapies in IgAN

Inclusion Criteria:

• Adult patients, male or female, with a biopsy proven IgA nephropathy.
• Primitive and secondary forms can be included
• Regardless of the date of diagnosis and the level of kidney function
• With or without past of kidney transplantation
• Followed in the Nephrology Department, Strasbourg University Hospital
• Signed informed consent

Exclusion Criteria:

• Active or recent infectious or inflammatory syndrome (<2 months), recent vaccination (<2 months), ongoing acute humoral rejection treatment, treatment with plasma exchanges (<2 months), current treatment with complement inhibitors
• Impossibility of giving informed information (emergency situation, difficulties in understanding, etc.)
• Subject under safeguard of justice, guardianship or curatorship

Adult patients with a histologically proven diagnosis of IgA nephropathy, with or without kidney transplantation history followed in the Nephrology Department of Strasbourg University Hospital.