Recurrence of membranoproliferative glomerulonephritis after renal transplantation in Denys-Drash

A critical re-analysis of cases of post-transplantation recurrence in genetic nephrotic syndrome

BACKGROUND

Genetic defects in podocyte proteins account for up to 30% of steroid-resistant nephrotic syndrome (SRNS) in the paediatric population. Most children with genetic SRNS are resistant to immunosuppression and at high risk of progression to stage 5 chronic kidney disease. Kidney transplantation is often the treatment of choice. The possibility of post-transplantation disease recurrence in genetic SRNS remains controversial, and poses fundamental questions about disease biology.

METHODS

We critically evaluated the published cases of post-transplantation recurrence in genetic patients, particularly testing 'mutations' against the most recent population variant databases, in order to clarify the diagnoses, and compare the clinical courses and responses to therapy.

RESULTS

Biallelic pathogenic variants in NPHS1 leading to a complete absence of nephrin were the most commonly reported and best understood instance of nephrotic syndrome occurring post-transplantation. This is an immune-mediated process driven by antibody production against the novel nephrin protein in the allograft. We also identified a number of plausible reported cases of post-transplantation recurrence involving pathogenic variants in NPHS2 (8 patients, biallelic), one in WT1 (monoallelic) and one in NUP93 (biallelic). However, the mechanism for recurrence in these cases remains unclear. Other instances of recurrence in genetic disease were difficult to interpret due to differing clinical criteria, inclusion of patients without true pathogenic variants or the influence of other factors on renal outcome.

CONCLUSIONS

Overall, post-transplantation recurrence remains very rare in patients with genetic SRNS. It appears to occur later after transplantation than in other patients and usually responds well to plasmapheresis with a good renal outcome.

Focal Segmental Membranoproliferative Glomerulonephritis: A Histological Variant of Denys-Drash Syndrome

Introduction: Denys-Drash Syndrome (DDS) consists of a triad of pseudohermaphroditism, Wilms'tumor and nephropathy. This condition may manifest as a complete triad or in an incomplete form; with either one or a combination of the above features. The characteristic glomerular abnormality in DDS is diffuse mesangial sclerosis (DMS).Case report: We report two cases of DDS with focal membranoproliferative glomerulonephritis (MPGN). Both of our cases were males with ambiguous genitalia. They had a similar heterozygous germline mutation in exon 9 of WT1, c.1180C>T, p.R394W; a known mutation hotspot for DDS. Case 1 had nephropathy at the age of 4 years and Case 2 at 2.5 years with different rates of progression to end-stage renal failure. Conclusion: Our findings, in combination with other reports, illustrate the clinicopathological heterogeneity of DDS. There are no universal recommendations for optimal management of patients with DDS due to the inability to accurately predict affected individuals' progress.

Immune-complex glomerulonephritis with a membranoproliferative pattern in Frasier syndrome: a case report and review of the literature

Background

Mutations in the Wilms tumor 1 gene cause a spectrum of podocytopathy ranging from diffuse mesangial sclerosis to focal segmental glomerulosclerosis. In a considerable fraction of patients with Wilms tumor 1 mutations, the distinctive histology of immune-complex-type glomerulonephritis has been reported. However, the clinical relevance and etiologic mechanisms remain unknown.

Case presentation

A 5-year-old child presented with steroid-resistant nephrotic range proteinuria. Initial renal biopsy revealed predominant diffuse mesangial proliferation with a double-contour and coexisting milder changes of focal segmental glomerulosclerosis. Immunofluorescence and electron microscopy revealed a full-house-pattern deposition of immune complexes in the subendothelial and paramesangial areas. Serial biopsies at 6 and 8 years of age revealed that more remarkable changes of focal segmental glomerulosclerosis had developed on top of the initial proliferative glomerulonephritis. Identification of a de novo Wilms tumor 1 splice donor-site mutation in intron 9 (NM_024426.6:c.1447 + 4C > T) and 46,XY-gonadal dysgenesis led to the diagnosis of Frasier syndrome.

Conclusions

Our findings, together with those of others, point to the importance of heterogeneity in clinicopathological phenotypes caused by Wilms tumor 1 mutations and suggest that immune-complex-mediated membranoproliferative glomerulopathy should be considered as a histological variant.