Recurrence of severe steroid dependency in cyclosporin A-treated childhood idiopathic nephrotic syndrome

Background. In patients with steroid-dependent nephrotic syndrome (SDNS), long-term remission (LTR) can usually be achieved with cyclosporin A (CSA), after alternative treatment with cytotoxic drugs or levamisole has failed. Nevertheless, severe SDNS recurs in some patients despite CSA maintenance therapy. Few data are available on the clinical course and treatment strategies in these patients. Methods. We carried out a retrospective chart analysis of 46 patients with SDNS treated with CSA, after failure of cyctotoxic treatment with cyclophosphamide (CPO). Median age at primary manifestation was 3.0 years (range 0.8-6.9) and median current age is 20.4 years (range 8.6-29.1). Patients were recruited from three centres caring for a total of 186 patients with steroid-sensitive nephrotic syndrome. Results. In 14 of the 46 patients (30%; 10 male), severe SDNS recurred again despite CSA maintenance therapy. Seven patients relapsed beyond the age of 18 years. Nine of 14 patients received a further course of cytotoxic treatment as first intervention: six were treated with chlorambucil (CLA) and three with CPO. Four of the CLA-treated patients remained in LTR in contrast to none after CPO. Five patients received levamisole after CSA: only one went into LTR, while in one other CSA could be discontinued although further relapses occurred. One further patient was switched to CLA after levamisole, finally inducing LTR. Overall, six patients required two or more drugs, and in four of these CSA maintenance ultimately had to be restarted. Conclusion. We conclude that SDNS can recur in patients despite CSA maintenance therapy. Treatment strategies for this subgroup of patients are complex and should be standardized to optimize long-term outcome. A subgroup of patients with childhood SDNS continues to relapse into adulthoo

Mutation analysis of 18 nephronophthisis associated ciliopathy disease genes using a DNA pooling and next generation sequencing strategy

Background Nephronophthisis associated ciliopathies (NPHP-AC) comprise a group of autosomal recessive cystic kidney diseases that includes nephronophthisis (NPHP), Senior-Loken syndrome (SLS), Joubert syndrome (JBTS), and Meckel-Gruber syndrome (MKS). To date, causative mutations in NPHP-AC have been described for 18 different genes, rendering mutation analysis tedious and expensive. To overcome the broad genetic locus heterogeneity, a strategy of DNA pooling with consecutive massively parallel resequencing (MPR) was devised.Methods In 120 patients with severe NPHP-AC phenotypes, five pools of genomic DNA with 24 patients each were prepared which were used as templates in order to PCR amplify all 376 exons of 18 NPHP-AC genes (NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, GLIS2, RPGRIP1L, NEK8, TMEM67, INPP5E, TMEM216, AHI1, ARL13B, CC2D2A, TTC21B, MKS1, and XPNPEP3). PCR products were then subjected to MPR on an Illumina Genome-Analyser and mutations were subsequently assigned to their respective mutation carrier via CEL I endonuclease based heteroduplex screening and confirmed by Sanger sequencing.Results For proof of principle, DNA from patients with known mutations was used and detection of 22 out of 24 different alleles (92% sensitivity) was demonstrated. MPR led to the molecular diagnosis in 30/120 patients (25%) and 54 pathogenic mutations (27 novel) were identified in seven different NPHP-AC genes. Additionally, in 24 patients only single heterozygous variants of unknown significance were found.Conclusions The combined approach of DNA pooling followed by MPR strongly facilitates mutation analysis in broadly heterogeneous single gene disorders. The lack of mutations in 75% of patients in this cohort indicates further extensive heterogeneity in NPHP-AC

Recurrence of severe steroid dependency in cyclosporin A-treated childhood idiopathic nephrotic syndrome

Background. In patients with steroid-dependent nephrotic syndrome (SDNS), long-term remission (LTR) can usually be achieved with cyclosporin A (CSA), after alternative treatment with cytotoxic drugs or levamisole has failed. Nevertheless, severe SDNS recurs in some patients despite CSA maintenance therapy. Few data are available on the clinical course and treatment strategies in these patients. Methods. We carried out a retrospective chart analysis of 46 patients with SDNS treated with CSA, after failure of cyctotoxic treatment with cyclophosphamide (CPO). Median age at primary manifestation was 3.0 years (range 0.8-6.9) and median current age is 20.4 years (range 8.6-29.1). Patients were recruited from three centres caring for a total of 186 patients with steroid-sensitive nephrotic syndrome. Results. In 14 of the 46 patients (30%; 10 male), severe SDNS recurred again despite CSA maintenance therapy. Seven patients relapsed beyond the age of 18 years. Nine of 14 patients received a further course of cytotoxic treatment as first intervention: six were treated with chlorambucil (CLA) and three with CPO. Four of the CLA-treated patients remained in LTR in contrast to none after CPO. Five patients received levamisole after CSA: only one went into LTR, while in one other CSA could be discontinued although further relapses occurred. One further patient was switched to CLA after levamisole, finally inducing LTR. Overall, six patients required two or more drugs, and in four of these CSA maintenance ultimately had to be restarted. Conclusion. We conclude that SDNS can recur in patients despite CSA maintenance therapy. Treatment strategies for this subgroup of patients are complex and should be standardized to optimize long-term outcome. A subgroup of patients with childhood SDNS continues to relapse into adulthoo