Supplementary Material for: Fibronectin glomerulopathy: A First African Case Report

Introduction Fibronectin glomerulopathy is a rare autosomal dominant disorder characterized by abnormal deposition of fibronectin within the kidney. It is associated with several variant mutations in the FN1 gene. It is a disorder predominantly characterized by proteinuria that can reach the nephrotic range, and it has been primarily described in Asian and White populations. Here, we report a case of fibronectin glomerulopathy from Ethiopia, which, to our knowledge, is the first ever reported in Africa. Case presentation A 17-year-old Ethiopian female presented with generalized body swelling and nephrotic range proteinuria. Secondary causes of nephrotic syndrome were ruled out but kidney biopsy was not performed early because of financial constraints. The patient received initial treatments with RASi (renin angiotensin inhibitor) and diuretics followed by steroids and tacrolimus; but lacked a clear response. Eventually, a kidney biopsy and examination at a pathology laboratory in India revealed extensive periodic acid Schiff-positive but Jones’ methenamine silver- and Congo red-negative mesangial and capillary wall deposits which stained strongly for fibronectin on immunohistochemistry. A diagnosis of fibronectin glomerulopathy was made. Conclusion Diagnosing fibronectin glomerulopathy could be challenging in many developing nations due to a lack of proper pathologic and genetic testing infrastructure. Improving local health infrastructure for kidney tissue diagnosis could improve diagnostic accuracy, better guide management, and help avoid the administration of unnecessary medications with a potential for serious adverse events.