Abstract 1956 Nephrology Platform, Sunday, 5/2

Background: Idiopathic nephrotic syndrome (INS) is the most common form of nephrotic syndrome in children. Although it is regarded as a sporadic disease, familial forms have been reported. A gene (SRN1) responsible for steroid-resistant INS with renal failure (SRN) has been mapped to chromosome 1, thus demonstrating the existence of a subgroup of autosomal-recessive nephrosis (Fuchshuber et al. Hum Mol Genet 11: 2155-2158 (1995)). However, genetic heterogeneity could be demonstrated, suggesting that further genes are involved in SRN.

Patients: We have collected 35 multiplex INS-families with a total of 73 affected individuals. Families were classified using clinical criteria like age of onset, response to steroid treatment, renal morphology, progression into renal failure, recurrence after renal transplantation. 24 families were tested for linkage to SRNI on chromosome 1 (table).

Table 1 No caption available
Full size table

Results: The families were classified into two groups, SRN (19×) and steroid-sensitive INS (SSN: 16×). Intra- and interfamilial variability in both groups was low. For linkage studies, the first group was subdivided into SRN and SRN without renal failure (non-SRN) (table): Linkage to SRN1 in 24 INS-families (+ linkage, - no linkage)

Conclusion: Not only SRN, but also SSN represents a clinically and genetically distinct subgroup of autosomal-recessive hereditary nephrosis, appropriate for linkage analysis. The investigation of rare familial forms of INS using molecular biology techniques (positional cloning) may help to clarify the classification of INS.