The term "Monoclonal Gammopathies of Renal Significance" (MGRS) describes a group of diseases characterized by the presence of an immunoglobulin or monoclonal immunoglobulin fraction that has the ability to cause renal damage.

It is important to diagnose MGRS correctly and early as renal survival depends on the renal function present at the time of diagnosis and it is necessary to establish a specific treatment that aims to stop the progression of the damage. organ and restoration of renal function.

To date, there are no targeted therapeutic strategies that can prevent the formation of deposits or that can eliminate the deposits already present in the kidney, which constitute the etiopathogenetic factor of these pathologies. Therefore, the only valid therapeutic option is to act against the clone of B lymphocytes underlying the nephrological pathology, although it is not a clone with such requirements to be able to define it as a tumor.

Therefore, given the absence of a well-defined policy in the therapy of MGRS and the doubts present on the validity of a therapeutic approach aimed at the suppression of a plasma cell clone, the investigators decided to carry out an observational retrospective study with the aim of describing, in a large series of MGRS treated with oncohematological therapy, the renal and overall outcome of patients and identify any presenting prognostic characteristics that can help improve the diagnosis of these disorders and the long-term survival of patients.

The group will be compared with patients suffering from renal disease associated with oncohematological diseases with full clinical expression (multiple myeloma and B cell lymphomas) which produce monoclonal component and who have been treated according to the established specific schemes of each disease.

The study will have a total duration of 12 months. It will analyze the data of the patients included in the clinical charts from 01/01/2010 to 31/12/2020. A total of 120 patients and 60 pathological controls will be enrolled (2:1 ratio), expected total number of patients from the centers participating in the study enrolled through the outpatient clinics of the Departments of the study.

The variables considered in the study are routine laboratory data (renal function, electrophoresis of serum and urinary proteins with immunofission, serum free light chains and their ratio, proteinuria 24 h serum albumin), clinical and anamnestic data, data on current drug therapy and description of renal biopsy characteristics using a predefined database with statistical analysis of data.

Inclusion Criteria:

• Renal biopsy diagnosis of MGRS or disease linked to multiple myeloma and B cell lymphoma between 01/01/2010 and 31/12/2020 (for patient group)
• Renal biopsy diagnosis of nephropathy linked to onco-haematological pathology with full clinical expression (eg Multiple Myeloma, B-cell Lymphoma) between 01/01/2010 and 31/12/2021 (for control group);
• Age greater than or equal to 18 years;
• Informed consent freely granted and acquired before the start of the study.

Exclusion Criteria:

• Patients who do not meet the relevant inclusion criteria and who do not have an established diagnosis of MGRS or disease related to multiple myeloma and B-cell lymphoma will be excluded from the study.

This is a large series of patients with Monoclonal Gammopathies of Renal Significance treated with oncohematological therapy; this group will be compared with patients suffering from renal disease associated with oncohematological diseases with full clinical expression (multiple myeloma and B cell lymphomas) which produce monoclonal component and who have been treated according to the established specific schemes of each disease.