Unilateral nephrectomy for young infants with congenital nephrotic syndrome of the Finnish type

The clinical characteristics of patients with congenital nephrotic syndrome secondary to NPHS1 mutation: Is nephrectomy still a therapeutic option for selected cases?

BACKGROUND

Managing congenital nephrotic syndrome (CNS) remains a clinical challenge. While albumin infusions and nephrectomy have been long-standing treatments, a conservative approach is increasingly favored. This study aimed to compare clinical outcomes between nephrectomy (Nx) and non-Nx in patients with bi-allelic NPHS1 mutations.

METHODS

This retrospective cohort study included 29 pediatric CNS patients (15 female, 14 male) with confirmed NPHS1 mutations. Clinical parameters including albumin infusion requirements, infections, hospitalizations, growth, and survival rates were analyzed in the Nx and non-Nx groups.

RESULTS

The median age at the time CNS was diagnosed was 29 days (IQR: 11-62 days). In all, 24 patients (82.8%) had homozygous NPHS1 mutations and 5 (17.2%) had compound heterozygous NPHS1 mutations. None of the patients had Fin-major mutation (i.e., p. Leu41 Aspfs*50). Unilateral/bilateral nephrectomy was performed in 16 patients. At 12 months post-nephrectomy the number of albumin infusions required, infections, and hospitalizations decreased significantly in the Nx group, as compared to the pre-nephrectomy period (p = 0.001, p = 0.027, and p = 0.004, respectively). Among the 13 (44.8%) patients in the non-Nx group, at 12 months after CNS was diagnosed the number of serum albumin infusions required significantly decreased (p = 0.007); however, the number of infections and hospitalization did not differ significantly (p = 0.589 and p = 0.5, respectively). Receiver operating characteristic (ROC) analysis showed that requiring albumin infusions ≥ 14 days/month predicted the decision to perform nephrectomy with 68% accuracy (73% sensitivity and 62% specificity).

CONCLUSIONS

Nephrectomy reduces albumin infusions, infections, and hospitalizations, suggesting it may be a beneficial treatment for selected CNS patients with NPHS1 mutations.

A Case of Congenital Nephrotic Syndrome with Crescents Caused by a Novel Compound Heterozygous Pairing of NPHS1 Genetic Variants

Congenital nephrotic syndrome is an autosomal recessive inherited disorder that manifests as steroid-resistant massive proteinuria in the first three months of life. Defects in the glomerular filtration mechanism are the primary etiology. We present a child who developed severe nephrotic syndrome at two weeks of age and eventually required a bilateral nephrectomy. Genetic testing revealed compound heterozygous variants in NPHS1 including a known pathogenic variant and a missense variant of uncertain significance. Light microscopy revealed crescent formation-an atypical finding in congenital nephrotic syndrome caused by nephrin variants-in addition to focal segmental and global glomerulosclerosis. Electron microscopy showed diffuse podocyte foot process effacement. Confocal and Airyscan immunofluorescence microcopy showed aggregation of nephrin in the podocyte cell body that is not a result of diffuse podocyte foot process effacement as seen in minimal change disease. These findings confirm the novel variant as pathogenic.

Clinical presentation and management of nephrotic syndrome in the first year of life: A report from the Pediatric Nephrology Research Consortium

BACKGROUND AND OBJECTIVES

Nephrotic syndrome (NS) in the first year of life is called congenital (CNS) if diagnosed between 0-3 months, or infantile (INS) if diagnosed between 3-12 months of age. The aim of this study was to determine if there were clinically meaningful differences between CNS and INS patients, regarding clinical presentation, management and outcomes.

DESIGN SETTING PARTICIPANTS AND MEASUREMENTS

Eleven Pediatric Nephrology Research Consortium sites participated in the study, using IRB-approved retrospective chart reviews of CNS and INS patients born between 1998 and 2019. Data were collected on patient characteristics, pertinent laboratory tests, provided therapy, timing of unilateral/bilateral nephrectomy and initiation of renal replacement therapy (RRT).

RESULTS

The study included 69 patients, 49 with CNS and 20 with INS, with a median age at diagnosis of 1 and 6 months, respectively. Management for the two groups was similar regarding nutrition, thyroxin supplementation, immunoglobulin administration, and thrombosis prophylaxis. Within the first 2 months after diagnosis, daily albumin infusions were used more often in CNS vs. INS patients (79 vs. 30%; p = 0.006), while weekly infusions were more common in INS patients (INS vs. CNS: 50 vs. 3%; p = 0.001). During the 6 months preceding RRT, albumin infusions were more frequently prescribed in CNS vs. INS (51 vs. 15%; p = 0.007). Nephrectomy was performed more often in CNS (78%) than in INS (50%; p = 0.02). End-stage kidney disease tended to be more common in children with CNS (80%) vs. INS (60%; p = 0.09).

CONCLUSION

Compared to INS, patients with CNS had a more severe disease course, requiring more frequent albumin infusions, and earlier nephrectomy and RRT. Despite center-specific variations in patient care, 20-40% of these patients did not require nephrectomy or RRT.