Clear evidence of LAMA5 gene biallelic truncating variants causing infantile nephrotic syndrome

Background: Pathogenic variants in single genes encoding podocyte-associated proteins have been implicated in about 30% of steroid resistant nephrotic syndrome (SRNS) patients in children. However, LAMA5 gene biallelic variants have been identified in only 7 patients so far, and most are missense variants of unknown significance. Furthermore, no functional analysis had been conducted for all but one of these variants. Here, we report three patients with LAMA5 gene biallelic truncating variants manifesting infantile nephrotic syndrome and one SRNS case with biallelic LAMA5 missense variants. Methods: We conducted comprehensive gene screening of Japanese patients with severe proteinuria. Using targeted next-generation sequencing, 62 podocyte-related genes were screened in 407 unrelated patients with proteinuria. For the newly discovered LAMA5 variants, we conducted in vitro heterotrimer formation assays. Results: Biallelic truncating variants in the LAMA5 gene (NM_005560) were detected in 3 patients from 2 families. All patients presented with proteinuria within 6 months of age. Patients 1 and 2 were siblings possessing a nonsense variant (c.9232C>T, p.(Arg3078*)) and a splice site variant (c.1282+1G>A) that led to exon 9 skipping and a frameshift. Patient 3 had a remarkable irregular contour of the glomerular basement membrane. She was subsequently found to have a nonsense variant (c.8185C>T, p.(Arg2720*)) and the same splice site variant in patients 1 and 2. By in vitro heterotrimer formation assays, both truncating variants produced smaller laminin α5 proteins that nevertheless formed trimers with laminin β1 and γ1 chains. Patient 4 showed SRNS at the age of eight and carried compound heterozygous missense variants (c.1493C>T, p.(Ala498Val) and c.8399G>A, p.(Arg2800His)). Conclusions: Our patients showed clear evidence of biallelic LAMA5 truncating variants causing infantile nephrotic syndrome. We also discerned the clinical and pathological characteristics observed in LAMA5-related nephropathy. LAMA5 variant screening should be performed in congenital/infantile nephrotic syndrome patients.

Hereditary Congenital and Infantile Nephrotic Syndrome in Children: Strategy of Management with New Possibilities for Genetic Diagnosis and Therapy

Due to the worldwide genetic research, the fundamental information was obtained regarding the pathogenesis of the hormone-resistant congenital and infantile nephrotic syndrome in children. The mutations in the genes encoding the main components of the basement membrane of the kidney glomeruli, structural and functional podocyte proteins are responsible for the development of the congenital and infantile nephrotic syndrome with the typical histologic pattern of the diffuse mesangial sclerosis or focal segmental glomerulosclerosis. In accordance with the evidence-based international strategy, the clinical phenotyping combined with the targeted genetic analysis is the diagnosis standard for the hereditary nephrotic syndrome in children that are recommended to perform the genetic analysis prior to start of the steroid therapy and prior to the kidney biopsy. The early genetic diagnosis assures the personalized approach to the choice of the therapies considering the genotype and phenotype specifics of the congenital or infantile nephrotic syndrome in the particular child. The up-to-date strategy for the management of such children provides the carrying out of the conservative therapy and early transplantation of the related kidney when reaching 10-15 kg body weight (in this case, the kidneys are removed and transplanted during the same surgery), or the bilateral nephrectomy simultaneously or one stepped, then the second kidney and peritoneal dialysis, then kidney transplantation for the children reached 10-15 kg body weight. According to ESPN / ERA-EDTA register (2016), the 5-year survival rate of the children with the congenital nephrotic syndrome caused by NPHS1 gene mutation is 91% after kidney transplantation, 89% after allograft. The solutions for the pressing challenge of the domestic pediatrics are as the following: introduce the international strategy into the practice of the children management with the congenital and infantile nephrotic syndrome with the new possibilities of the genetic diagnosis and therapy replacing the kidney function; enhance the kidney transplantation and its availability; carry out the epidemiological studies of the hereditary nephrotic syndrome.

Fungal peritonitis in children on peritoneal dialysis at a tertiary care Centre

Background Fungal peritonitis (FP) is an infrequent but serious complication in children undergoing peritoneal dialysis (PD). This study aimed to explore the risk factors, clinical manifestations, causative organisms, fungal susceptibility findings, and outcomes of FP in children from Saudi Arabia. Methods In this case–control study, the medical records and laboratory results of paediatric patients aged 0–14 years who underwent PD were reviewed for FP episodes. All FP episodes were matched with PD-related bacterial peritonitis episodes (1:4 ratio). Results A total of 194 episodes of PD-related peritonitis occurred between 2007 and 2017, among which 11 were FP episodes (5.6%), representing a rate of 0.03 episodes per patient-year. Of these 11 episodes, 9 were caused by Candida species (82%). Compared with the bacterial peritonitis group, the FP group had a higher proportion of patients with congenital/infantile nephrotic syndrome (p = 0.005) and those younger than 5 years of age (p = 0.001). We observed a higher rate of catheter removal in the FP group than in the bacterial peritonitis group (p < 0.001); however, 1 patient died despite catheter removal. Moreover, 75% of Candida species isolates were susceptible to fluconazole. Conclusions This study revealed that FP is associated with a significant risk of peritoneal membrane failure among children undergoing PD. Therefore, early diagnosis and prompt management are essential. We also found that congenital/infantile nephrotic syndrome and young age (5 years old or younger) were risk factors for FP in children undergoing PD.

A cross-sectional nationwide survey of congenital and infantile nephrotic syndrome in Japan

Background: Congenital nephrotic syndrome (CNS) and infantile nephrotic syndrome (INS) cause substantial morbidity and mortality. In Japan, there is a lack of knowledge regarding the characteristics of CNS and INS. This study aimed to clarify the characteristics of CNS and INS in Japan.Methods: This cross-sectional nationwide survey obtained data from 44 institutions in Japan managing 92 patients with CNS or INS, by means of two survey questionnaires sent by postal mail. Patients aged <16 years by 1 April 2015, with a diagnosis of CNS or INS, were included in this study. The primary outcome was end-stage kidney disease.Results: A total of 83 patients with CNS or INS were analyzed. The most frequent disease type was non-Finnish (60.2%); 33 patients (39.8%) had Finnish type. Among those with non-Finnish-type disease, 26 had no syndrome and 24 had a syndrome, of which the most frequent was Denys–Drash syndrome (70.8%). Patients with non-Finnish-type disease with syndrome showed the earliest progression to end-stage kidney disease compared with the other two groups, whereas patients with non-Finnish-type disease without syndrome progressed more slowly compared with the other two groups. In the Finnish-type group, the disease was diagnosed the earliest; a large placenta was reported more frequently; genetic testing was more frequently performed (93.8%); mental retardation was the most frequent extra-renal symptom (21.2%); and thrombosis and infection were more frequent compared with the other groups. Patients with non-Finnish-type disease with syndrome had a higher frequency of positive extra-renal symptoms (79.2%), the most common being urogenital symptoms (54.2%). Treatment with steroids and immunosuppressants was more frequent among patients with non-Finnish-type disease without syndrome. Two patients with non-Finnish-type disease without syndrome achieved complete remission. In all groups, unilateral nephrectomy was performed more often than bilateral nephrectomy and peritoneal dialysis was the most common renal replacement therapy.Conclusions: The present epidemiological survey sheds light on the characteristics of children with CNS and INS in Japan. A high proportion of patients underwent genetic examination, and patient management was in accord with current treatment recommendations and practices.Trial registration: Not applicable.

A cross-sectional nationwide survey of congenital and infantile nephrotic syndrome in Japan

Background: Congenital nephrotic syndrome (CNS) and infantile nephrotic syndrome (INS) cause substantial morbidity and mortality. In Japan, there is a lack of knowledge regarding the characteristics of CNS and INS. This study aimed to clarify the characteristics of CNS and INS in Japan.Methods: This cross-sectional nationwide survey obtained data from 44 institutions in Japan managing 92 patients with CNS or INS by means of two survey questionnaires sent by postal mail. Patients aged <16 years by 1 April 2015, with a diagnosis of CNS or INS, were included in this study. The primary outcome was end-stage kidney disease.Results: A total of 83 patients with CNS or INS were analyzed. The most frequent disease type was non-Finnish (60.2%); 33 patients (39.8%) had Finnish type. Among those with non-Finnish-type disease, 26 had no syndrome and 24 had a syndrome, of which the most frequent was Denys–Drash syndrome (70.8%). Patients with non-Finnish-type disease with syndrome showed the earliest progression to end-stage kidney disease compared with the other two groups, whereas patients with non-Finnish-type disease without syndrome progressed more slowly compared with the other two groups. In the Finnish-type group, the disease was diagnosed the earliest; a large placenta was reported more frequently; genetic testing was more frequently performed (93.8%); mental retardation was the most frequent extra-renal symptom (21.2%); and thrombosis and infection were more frequent compared with the other groups. Patients with non-Finnish-type disease with syndrome had a higher frequency of positive extra-renal symptoms (79.2%), the most common being urogenital symptoms (54.2%). Treatment with steroids and immunosuppressants was more frequent among patients with non-Finnish-type disease without syndrome. Two patients with non-Finnish-type disease without syndrome achieved complete remission. In all groups, unilateral nephrectomy was performed more often than bilateral nephrectomy and peritoneal dialysis was the most common renal replacement therapy.Conclusions: The present epidemiological survey sheds light on the characteristics of children with CNS and INS in Japan. A high proportion of patients underwent genetic examination, and patient management was in accord with current treatment recommendations and practices.Trial registration: Not applicable.