# Clinicopathological Features of Hereditary Nephritis in the Iranian Population: Analysis of a 14-Year Survey in Kidney Biopsies From a Large Referral Center

## TL;DR

This study analyzed kidney biopsies from Iran to better understand hereditary nephritis, finding that electron microscopy and immunostaining help diagnose and differentiate subtypes.

## Contribution

The study provides clinicopathological insights into hereditary nephritis in the Iranian population using a 14-year biopsy dataset.

## Key findings

- Hereditary nephritis accounted for 5.4% of kidney biopsies, with a mean age of 13.78 years.
- Electron microscopy and immunostaining improved diagnostic accuracy for Alport syndrome subtypes.
- X-linked Alport syndrome was the most common diagnosis among cases with suspicious electron microscopy findings.

## Abstract

Hereditary nephritis (HN), including Alport syndrome (AS) and thin basement membrane nephropathy (TBMN), is a rare genetic cause of hematuria. A definitive diagnosis requires electron microscopy (EM). Therefore, the clinical characteristics of these conditions are less known. This study aimed to determine the percentage and clinicopathological features of HN in patients from a referral center in Iran.

We checked kidney biopsy reports from 2007 to 2021 and extracted cases with HN. Fresh specimens of the cases diagnosed in the last two years were stained by immunofluorescence (IF) for collagen type IV alpha chains. EM findings in these cases were re-evaluated and categorized as diffuse glomerular basement membrane (GBM) thinning, definite, and suspicious features of AS.

We analyzed 3884 pathology reports of kidney biopsies from 2007 to 2021 and identified 210 patients (5.4%) with HN, with a mean age of 13.78±12.42 years old. Hematuria with proteinuria (53.3%), isolated hematuria (44.2%), and proteinuria with hematuria and increased creatinine (2.5%) were found in these patients. The re-evaluation of EM findings revealed GBM thinning, definite, and suspicious findings of AS in 37.5%, 43.8%, and 18.8% cases, respectively. The most common diagnosis in 32 cases after the IF study was X-linked AS (71.9%), and 6.2% of cases were autosomal recessive AS. TBMN and autosomal dominant AS remained the differential diagnoses in 21.9%.

It was found that EM is helpful for the primary diagnosis of patients with definite AS. Immunostaining improves the diagnostic sensitivity for the differentiation of those with suspicious EM findings and determines the inheritance pattern. However, a multidisciplinary approach for a subset of cases is required for the best diagnosis and management.