Multiple gene mutations in cytomegalovirus positive infantile nephrotic syndrome: a case report

The term 搃nfantile� is used for those cases of nephrotic syndrome (NS) that manifest from 3 months to 1 year of age. These are rare diseases attributable to both genetic and certain congenital infections. The prognosis depends on the type of mutation and whether remission occurs with specific therapy in the latter. However, multiple other gene mutations may be found associated with these that hold individual significance. Here, we report a case of an 11-month-old child with infantile NS having novel gene mutations NPHS 2 gene and the gut-associated lymphoid tissues (GALT) on Exon 4 and Exon 5 gene respectively. The presence of hepatomegaly and poor nutritional status instigated us to investigate congenital infections. Positive IgM and IgG values of cytomegalovirus (CMV) in the TORCH profile and a positive urinary polymerase chain reaction confirmed CMV infection, though we were unable to establish whether it was congenital or acquired postnatally. The child was managed with injectable gancyclovir along with supportive therapy which showed partial remission after a period of 10 days and discharge on angiotensin converting enzyme (ACE) inhibitor and diuretic. The coexistence of the multiple gene mutations might have caused the severity of the phenotype. Also, identification and treatment at earlier notice might have an impact on the outcome of the disease. The authors emphasize the importance of performing a genetic test in cases of infantile NS and also working up for acquired causes on an individualized basis.

Prenatal diagnosis of a fetus affected with Finnish type congenital nephrotic syndrome / 中华医学遗传学杂志

Objective@#To explore the genetic basis for a fetus suspected for congenital nephrotic syndrome of Finland (CNF).@*Methods@#Genomic DNA was extracted from peripheral and umbilical cord blood samples derived from both parents and the fetus. Potential variants were detected by using next-generation sequencing. Suspected variants were confirmed by Sanger sequencing.@*Results@#The fetus was found to carry compound heterozygous variants c. 1440+ 1G>A and c. 925G>T of the NPHS1 gene, which were respectively inherited from its mother and father.@*Conclusion@#Identification of the compound heterozygous NPHS1 variants has enabled diagnosis of CNF in the fetus and genetic counseling for the affected family.

Mutation of NPHS1 gene in a Chinese child with congenital nephrotic syndrome / 解放军医学杂志

Objective To analyze the mutations and characteristics of NPHS1 and NPHS2 genes in a child with congenital nephrotic syndrome (CNS). Methods Mutation analysis was made for all exons and exon/intron boundaries of NPHS1 and NPHS2 genes in a child and his parents as well as 50 unrelated adults with normal urine test results as control using PCR and direct sequencing techniques. Results No mutation of NPHS2 gene was detected, while a novel splice site mutation of IVS11+1G>A within intron 11 and a missense mutation within exon 8 (c.928G>A) in NPHS1 gene were detected in the child with CNS. Urinalysis was normal in child's mother, and it was found that c.928G>A (D310N) but no IVS11+1G>A heterozygous mutation, and his father was shown to have a normal urinalysis results, and the result of gene examination was IVS11+1G>A, but without c.928G>A (D310N) heterozygous mutation. All these IVS11+1 G>A and c.928G>A (D310N) mutations were not found in the 50 unrelated controls. Conclusions Two heterozygote mutations IVS11+1 G>A and c.928G>A in the NPHS1 gene have been identified in a child with CNS in the central region of China. The splice site mutation of IVS11+1 G>A is an novel genetic defect of CNS. It is necessary to look for mutations in NPHS1 gene in the children with CNS.

Mutational analysis of NPHS1 gene in children with sporadic steroid-resistant nephrotic syndrome in Southern Chinese Han ethnic group / 中华肾脏病杂志

Objective To elucidate the mutations of NPHS1 gene in children with sporadic steroid-resistant nephrotic syndrome (SRNS) in Southern Chinese Han ethnic group.Methods Peripheral blood samples were collected for genetic analysis from 40 patients with sporadic SRNS and 50 healthy volunteers as control.Genomic DNA was isolated from peripheral blood leucocytes.Twenty-nine exons and exon-intron boundaries of the NPHS1 gene were amplified by polymerase chain reaction.Mutational analysis was performed by DNA sequencing directly.Results Seven variants,928G＞A(D310N),2677A＞G (T893A),2869G＞C (V957L),IVS8+30C＞T,IVS21+14G＞A,IVS25-23C＞T and *142T＞C,of NPHS1 gene were found in 6 of 40 children with sporadic SRNS,whereas they were not found in 50 healthy controls.2677A ＞G,IVS8 +30C ＞T,IVS21 +14G＞A,IVS25-23C ＞T and *142T＞C were novel.Moreover,thirteen already reported NPHS1 polymorphisms,294C＞T,349G＞A,IVS3+15C＞T,IVS3+61A＞G,803G＞A,IVS8+68A＞G,1339G ＞A,1802G ＞C,2223C ＞T,2289C ＞T,IVS24 +36C ＞T,3315G＞A and IVS27 +45C ＞T,were detected in some patients and controls. Conclusions NPHS1 mutations in 6 of 40 children with sporadic SRNS in Southern Chinese Han ethnic group (15％) are detected.NPHS1 mutations are existed in Southern Chinese children,so it is necessary to perform the mutation analysis of NPHS1 gene in those children patients.

Síndromes nefróticos congénitos y hereditarios / Congenital and heritable nephrotic syndromes

En los últimos años se han identificado muchos síndromes nefróticos familiares y esporádicos que no responden a los tratamientos habituales (esteroides e inmunosupresores), evolucionan con relativa rapidez a la insuficiencia renal crónica y se producen por mutaciones genéticas. La mayoría de los síndromes nefróticos que se trasmiten genéticamente y que pueden ser congénitos, presentarse en el primer año de la vida, o en el niño mayor, son atribuidos a mutaciones en los genes NPHS1, NPHS2, WT1 y LAMB2. Otros síndromes nefróticos producidos por mutaciones genéticas pueden no manifestarse hasta la adultez. El objetivo fundamental de esta revisión fue llamar la atención sobre los síndromes nefróticos producidos por mutaciones genéticas en los que no sólo no se obtienen resultados con los tratamientos inmunosupresores, si no en los que dichos tratamientos pueden ser perjudiciales para el paciente

In past years many familial and sporadic nephrotic syndromes refractory to usual treatments (steroids and immunosuppressives), evolve quickly to a chronic renal failure produced by genetic mutations. Most of nephrotic syndromes genetically transmitted and that may be congenital, present in the first year of life or in the older child, are attributable to NPHS1, NPHS2, WT1 and KLAMB2 gen mutations. Other nephrotic syndromes produced by genetic mutations may not appear until adulthood. The main objective of present review was to alert on the nephrotic syndromes produced by genetic mutations without response to immunosuppressive treatments, but on those in which such treatment may be dangerous for patient

El síndrome nefrótico y el diagnóstico genético en pediatría / Inheritance genetics of nephrotic syndrome

Steroid-Resistant Nephrotic Syndrome (SRNS) is found in approximately 20 percent of patients with Nephrotic Syndrome (NS). Podocyte-gen mutations are diagnosed in a half of these children. Nephrin (NPHS1), podocin (NPHS2) and Wilms tumor suppressor gene (WT1) are the most frequently founded mutations. These patients usually progress to End Stage Renal Disease (ESRD). Objective: Current concepts in genetic diagnostic of NS in pediatrics are presented. A local experience is analyzed. In Chilean pediatric patients with SRNS, a mutational analysis of the NPHSl and NPHS2 gene was carried out by direct sequencing of the coding regions following polymerase chain reaction (PCR) amplification of genomic leukocyte DNA with flanking intronic primers. For WTl (exon 8 and exon 9), PCR of these fragments were done. Thirty-three patients were included, 17 males, 11,1 +/- 6.8 years. 54 percent of them developed ESRD, 12 patients were transplanted at the time of the analysis, 5 were under dialysis therapy, and 16 children correspond to ESRD Stage 3 and 4. Genetic analysis showed a gen mutation in 9 patients, NPHSl in 3 and NPHS2 in 6 of them. All genetic NS patients were cyclosporine-resistant. Post transplant relapse of NS was lower in genetic patients (p < 0.05). Conclusion: SRNS in children should be always evaluated from a genetic approach in order to avoid long-term immunosuppression, and to anticipate a clinical evolution after kidney transplantation.

En pediatría, el 20 por ciento de los pacientes portadores de Síndrome Nefrótico Idiopático son corticoresistentes (SNCR). Aproximadamente la mitad de ellos corresponden a mutaciones de genes que codifican proteínas del podocito. Las mutaciones más frecuentes corresponden al gen de la nefrina (NPHS1), la podocina (NPHS2) y del gen supresor del tumos de Wilms (WT1). Estas formas hereditarias no responden a tratamientos inmu-nosupresores y pueden progresar a enfermedad renal terminal (ERT). Objetivo: Revisar el estado actual del diagnóstico genético en Síndrome Nefrótico en niños, y presentar esta experiencia nacional de esta patología. Para el estudio de pacientes pediátricos chilenos, se realizó análisis de mutación del gen NPH2 por secuen-ciación directa de la regiones codificantes por PCR para la amplificación del DNA genómico leucocitario con partidores de acompañamiento intrónico. Para nefrina se procedió a extraer el DNA genómico, y se realizó la búsqueda de mutaciones de NPHSl por secuenciación directa de los 29 exones codificantes y las uniones intrónicas adyacentes, mientras que para el estudio de WTl se practicó el análisis mutacional de los exones 8 y 9, realizado por secuenciación directa del producto amplificado de WT1-PCR. Se han estudiado 33 pacientes provenientes de 29 familias, 17 varones, edad 11,1 +6,8 años. Dieciocho pacientes (54 por ciento) evolucionaron a ERT. Doce pacientes estaban trasplantados, 5 en diálisis, y 16 estaban en etapas 3-4 de enfermedad renal crónica. El estudio genético identificó mutaciones en 9 pacientes (27 por ciento), 3 correspondieron a NPHS1, 6 a NPHS2. Ningún caso con mutación respondió a tratamiento de Ciclosporina A (CsA), y las recaídas posttrasplante fueron significativamente menores en el grupo con mutación (+). Conclusión: Las mutaciones en estos genes deben ser estudiadas en cada niño con SNCR con el fin de evitar tratamientos prolongados e inefectivos, y anticipar la evolución después del trasplante renal.

Two Korean Infants with Genetically Confirmed Congenital Nephrotic Syndrome of Finnish Type

Congenital nephrotic syndrome is defined as nephrotic syndrome which manifests in utero or during the first 3 months of life. The prototype of congenital nephrotic syndrome is congenital nephrotic syndrome of Finnish type (CNF, OMIM #602716), which is caused by loss-of-function mutations of the nephrin gene (NPHS1). There have been few clinical case reports of CNF in Korea, but none of which was confirmed by genetic study. Here, we report two children with congenital nephrotic syndrome. Genetic analysis of the NPHS1 gene revealed compound heterozygous frame-shifting mutations (c.2156_2163 delTGCACTGC causing p.L719DfsX4 and c.3250_3251insG causing p.V1084GfsX12) in one patient and a missense mutation (c.1381G>A causing p.R460Q) and a nonsense mutation (c.2442C>G causing p.Y814X) in the other patient. The nonsense mutation was novel. The clinical courses of the patients were typical of CNF. This is the first report of genetically confirmed CNF in Korea to date. The early genetic diagnosis of CNF is important for proper clinical management of the patients and precise genetic counseling of the families.

Analysis of the intronic single nucleotide polymorphism rs#466452 of the nephrin gene in patients with diabetic nephropathy

We present the analysis of an intronic polymorphism of the nephrin gene and its relationship to the development of diabetic nephropathy in a study of diabetes type 1 and type 2 patients. The frequency of the single nucleotide polymorphism rs#466452 in the nephrin gene was determined in 231 patients and control subjects. The C/T status of the polymorphism was assessed using restriction enzyme digestions and the nephrin transcript from a kidney biopsy was examined. Association between the polymorphism and clinical parameters was evaluated using multivaríate correspondence analysis. A bioinformatics analysis of the single nucleotide polymorphism rs#466452 suggested the appearance of a splicing enhancer sequence in intron 24 of the nephrin gene and a modification of proteins that bind to this sequence. However, no change in the splicing of a nephrin transcript from a renal biopsy was found. No association was found between the polymorphism and diabetes or degree of renal damage in diabetes type 1 or 2 patients. The single nucleotide polymorphism rs#466452 of the nephrin gene seems to be neutral in relation to diabetes and the development of diabetic nephropathy, and does not affect the splicing of a nephrin transcript, in spite of a splicing enhancer site.