Two novel NPHS1 mutations in a Chinese family with congenital nephrotic syndrome

Genetic Variations and Clinical Features of NPHS1-Related Nephrotic Syndrome in Chinese Children: A Multicenter, Retrospective Study

Introduction: Few studies have addressed the genetic spectrum of NPHS1 variants in Chinese children with nephrotic syndrome. In this multicenter study, the clinical manifestations and features of NPHS1 variants in Chinese children with nephrotic syndrome were researched. Method: Genotypical and phenotypical data from 30 children affected by NPHS1 variants were collected from a multicenter registration system in China and analyzed retrospectively. Results: The patients were divided into two groups: congenital nephrotic syndrome (CNS [n = 24]) and non-CNS (early onset nephrotic syndrome [n = 6]). Renal biopsy was performed on four patients in the non-CNS group, revealing minimal change disease in three and focal segmental glomerulosclerosis in one. A total of 61 NPHS1 variants were detected, involving 25 novel variants. The "recurrent variants" included c.928G>A(p.Asp310Asn) in eight patients with CNS, followed by c.616C>A(p.Pro206Thr) in four, and c.2207T>C (p.Val736Ala) in three. Steroid treatment was applied in 29.2% (7/24)of the patients in the CNS group and 50% (3/6) of the patients in the non-CNS group. One patient in each group experienced complete remission but relapsed subsequently. Immunosuppressants were administered to three patients in the non-CNS group, eliciting an effective response. In the CNS group, three patients underwent renal transplantation and six died mainly from infection. Conclusion: Variants of NPHS1 cause CNS and early childhood-onset nephrotic syndrome. NPHS1 variants in Chinese individuals with nephrotic syndrome (NS) were mainly compound heterozygous variants, and c.928G>A(p.Asp310Asn) in exon 8 may act as a recurrent variant in the Chinese population, followed by c.616C>A(p.Pro206Thr) in exon 6. Steroids and immunosuppressants may be effective in selected patients.

A case report of congenital nephrotic syndrome caused by new mutations of NPHS1

Congenital nephrotic syndrome (CNS) is a rare autosomal recessive disorder that occurs in the first 0 to 3 months of life. The course of CNS is progressive, often leading to end-stage renal disease within 2 to 3 years. Most patients with CNS are resistant to glucocorticoids and immunosuppressive drugs. We report a girl aged 1 month and 20 days who was admitted to hospital with a history of abdominal distension and palpebral edema. She was diagnosed with CNS and administered a glucocorticoid (methylprednisolone) for 2 years. Targeted high-throughput next-generation sequencing showed mutations in the NPHS1 gene. She had a favorable outcome after 2 years of treatment. She has remained in complete remission for the last 6 months. From a clinical point of view, the outcome of CNS may be associated with end-stage renal disease or even death. Appropriate pharmacotherapy is beneficial to maintain a normal function and integrity of the glomerular barrier. An aggressive treatment plan is required to save the life of patients with CNS, even if a heterozygous mutation is detected by genetic analysis.

Gene mutation analysis in 12 Chinese children with congenital nephrotic syndrome

Background

Congenital nephrotic syndrome (CNS) is characterised by increased proteinuria, hypoproteinemia, and edema beginning in the first 3 months of life. Recently, molecular genetic studies have identified several genes involved in the pathogenesis of CNS. A systematic investigation of the genes for CNS in China has never been performed; therefore, we conducted a mutational analysis in 12 children with CNS,with the children coming from 10 provinces and autonomous regions in China.

Methods

Twelve children with CNS were enrolled from 2009 to 2016. A mutational analysis was performed in six children by Sanger sequencing in eight genes (NPHS1, NPHS2, PLCE1, WT1, LAMB2, LMXIB, COQ6 and COQ2) before 2014, and whole-exome sequencing was used from 2014 to 2016 in another six children. Significant variants that were detected by next generation sequencing were confirmed by conventional Sanger sequencing in the patients’ families.

Results

Of the 12 children, eight patients had a compound heterozygous NPHS1 mutation, one patient had a de novo mutation in the WT1 gene, and another patient with extrarenal symptoms had a homozygous mutation in the COQ6 gene. No mutations were detected in genes NPHS2, PLCE1, LAMB2, LMXIB, and COQ2 in the 12 patients.

Conclusions

This study demonstrates that the majority of CNS cases (67%, 8/12 patients) are caused by genetic defects, and the NPHS1 mutation is the most common cause of CNS in Chinese patients. A mutational analysis of NPHS1 should be recommended in Chinese patients with CNS in all exons of NPHS1 and in the intron-exon boundaries.

Three Novel Mutations in the NPHS1 Gene in Vietnamese Patients with Congenital Nephrotic Syndrome

Congenital nephrotic syndrome, a rare and severe disease, is inherited as an autosomal recessive trait. The disease manifests shortly after birth and occurs predominantly in families of Finnish origin but has now been observed in all countries and races. Mutations in the NPHS1 gene, which encodes nephrin, are the main causes of congenital nephrotic syndrome in patients. In this study, we report the first mutational analysis of the NPHS1 gene in three unrelated children from three different Vietnamese families. These patients were examined and determined to be suffering from congenital nephrotic syndrome in the Department of Pediatrics, Vietnam National Hospital of Pediatrics. All 29 exons and exon-intron boundaries of NPHS1 were analyzed by PCR and DNA sequencing. Genetic analysis of the NPHS1 gene revealed one compound heterozygous variant p.Glu117Lys, one heterozygous missense mutation p.Asp310Asn, and one heterozygous frame-shifting mutation (c.3250_3251insG causing p.Val1084Glyfs⁎12) in patient 1. In patient 2, one heterozygous variant p.Glu117Lys and one novel heterozygous missense mutation p.Ser324Ala were identified. Finally, a novel missense mutation p.Arg802Leu and a novel nonsense mutation (c.2442C>G causing p.K792⁎) were identified in patient 3.

Congenital nephrotic syndrome with a novel NPHS1 mutation

Congenital nephrotic syndrome of the Finnish type (CNF) is a rare autosomal recessive disorder. The incidence of CNF is relatively high in Finland but considerably lower in other countries. We encountered a male newborn with CNF, associated with compound heterozygous mutations in nephrosis 1, congenital, Finnish type (NPHS1). The patient was admitted to hospital as a preterm infant. Physical and laboratory findings fulfilled the diagnostic criteria of nephrotic syndrome, and were compatible with a diagnosis of CNF, but there was no family history of the disease. On genetic analysis of NPHS1 a paternally derived heterozygous frame-shift mutation caused by an 8 bp deletion, resulting in a stop codon in exon 16 (c.2156-2163 delTGCACTGC causing p.L719DfsX4), and a novel, maternally derived nonsense mutation in exon 15 (c.1978G>T causing p.E660X) were identified. Early genetic diagnosis of CNF is important for proper clinical management and appropriate genetic counseling.