This prospective study aims to investigate the role of IR-Seq in the diagnosis and disease monitoring in patients with IgA nephropathy.

Autoimmunity may play an important role in IgA nephropathy, and previous studies have shown that immune repertoire sequencing (IR-Seq) may help elucidate the dynamic changes of immune repertoire (IR) in autoimmune disease states. To further explore the potential application value of this technology, we will conduct a series of prospective studies to investigate the role of IR-Seq in the diagnosis and disease monitoring in patients with IgA nephropathy.

Inclusion Criteria:

1. IgA nephropathy:

1. Age: 18-80 years.
2. Patients diagnosed with primary IgA nephropathy by renal biopsy.
3. Estimated glomerular filtration rate (using the 2009 CKD-EPI formula) ≥30ml/min/1.73/m^2.
4. Obtain informed consent from patients. 2. Healthy Control: Gender, age and ethnicity matched health volunteers. 3. IgAN patients were further divided into 4 groups, as defined below:

1) Long-term stable patients:

Follow-up for at least 15 years and meet at least one of the following:

1. Annual eGFR loss rate <3ml/min/1.73m^2.
2. eGFR>90ml/min/1.73m^2. 2) Non-progressive IgAN patients:

Meet at least one of the following:

1. eGFR decrease of more than 50% from baseline (in the absence of other possible causes of kidney damage).
2. Annual eGFR loss rate >5ml/min/1.73m^2.
3. Progress to ESRD. 3) IgAN patients at low risk of disease progression: Proteinuria ≤ 1g/24h after 3 months of optimized supportive care. 4) IgAN patients at high risk of disease progression: Proteinuria > 1g/24h despite 3 months of optimized supportive care.

Exclusion Criteria:

1. Kidney biopsy shows crescentic IgAN or MCD-IgAN.;
2. Patients with secondary IgAN;
3. During pregnancy or lactation;
4. After kidney transplantation;
5. More than one serious acute infection in the psat 12 months;
6. Chronic infection;
7. Use of glucocorticosteroids and other immunosuppressive drugs within the last 6 months;
8. Incomplete medical history or clinical data.

Patients from Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, RenJi Hospital, Shanghai Zhongshan Hospital, Longhua Hospital Shanghai University of Traditional Chinese Medicine and Shanghai East Hospital