HLA alleles in frequently relapsing steroid-dependent and -resistant nephrotic syndrome in Egyptian children

Childhood Nephrotic Syndrome in Africa: Epidemiology, Treatment Trends, and Outcomes

Nephrotic syndrome is a common childhood glomerular disease that is associated with massive proteinuria and edema. Children with nephrotic syndrome are at risk of chronic kidney disease, disease-related complications, and treatment-related complications. Patients with frequently relapsing disease or steroid toxicity may require newer immunosuppressive medications. However, access to these medications is limited in many African countries owing to prohibitive cost, the need for frequent therapeutic drug monitoring, and a lack of appropriate facilities. This narrative review examines the epidemiology of childhood nephrotic syndrome in Africa, including trends in treatment and patient outcomes. In most of North Africa, as well as among White and Indian populations in South Africa, the epidemiology and treatment of childhood nephrotic syndrome closely resembles that of European and North American populations. Historically, secondary causes of nephrotic syndrome (eg, quartan malaria nephropathy and hepatitis B-associated nephropathy) were predominant among Blacks in Africa. Over time, the proportion of secondary cases has decreased, along with rates of steroid resistance. However, focal segmental glomerulosclerosis increasingly has been reported among patients with steroid resistance. There is a need for consensus guidelines for the management of childhood nephrotic syndrome in Africa. Furthermore, establishing an African nephrotic syndrome registry could facilitate monitoring of disease and treatment trends, and provide opportunities for advocacy and research to improve patient outcomes.

Relationships between the clinical phenotypes and genetic variants associated with the immunological mechanism in childhood idiopathic nephrotic syndrome: protocol for a prospective observational single-centre cohort study

INTRODUCTION

Idiopathic nephrotic syndrome (INS) is the most common glomerulopathy that results in childhood chronic kidney disease in China, but the relationships between different clinical phenotypes and immunological genetic variants observed in patients with INS are ambiguous and have not been well studied. A cohort study combined with whole exome sequencing might further identify the effects of immunological genetic variants on clinical phenotypes and treatment outcomes.

METHODS AND ANALYSIS

We describe a 3 year prospective observational single-centre cohort study to be conducted in the Children's Hospital of Chongqing Medical University in China. This study will recruit and investigate 336 patients with childhood-onset INS presenting with different clinical phenotypes. Whole exome sequencing will be conducted when patients progress to a confirmed clinical phenotype during follow-up. Relevant clinical and epidemiological data, as well as conventional specimens, will be collected at study entry and 1 month, 3 months, 6 months, 1 year, 2 years and 3 years after disease onset. After this cohort is generated, the immunological genetic variants of steroid-sensitive nephrotic syndrome without frequent relapse, steroid-resistant nephrotic syndrome and steroid-dependent/frequent relapse nephrotic syndrome will be evaluated.

ETHICS AND DISSEMINATION

The study protocol is approved by Ethics Committee of Children's Hospital of Chongqing Medical University (reference number 2018-140). The results will be disseminated through peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

ChiCTR1800019795.

Mutation analysis of NPHS1 in a worldwide cohort of congenital nephrotic syndrome patients

BACKGROUND

Congenital nephrotic syndrome (CNS) is defined as nephrotic syndrome that manifests within the first 3 months of life. Mutations in the NPHS1 gene encoding nephrin, are a major cause for CNS. Currently, more than 173 different mutations of NPHS1 have been published as causing CNS, affecting most exons.

METHODS

We performed mutation analysis of NPHS1 in a worldwide cohort of 20 families (23 children) with CNS. All 29 exons of the NPHS1 gene were examined using direct sequencing. New mutations were confirmed by demonstrating their absence in 96 healthy control individuals.

RESULTS

We detected disease-causing mutations in 9 of 20 families (45%). Seven of the families showed a homozygous mutation, while two were compound heterozygous. In another 2 families, single heterozygous NPHS1 mutations were detected. Out of 10 different mutations discovered, 3 were novel, consisting of 1 splice site mutation and 2 missense mutations.

CONCLUSION

Our data demonstrate that the spectrum of NPHS1 mutations is still expanding, involving new exons, in patients from a diverse ethnic background.

The relationship between the TGF-beta1 gene -509C/T polymorphism and tubulointerstitial damage resulting from primary nephrotic syndrome

BACKGROUND

The aim of this study was to investigate the correlation between the transforming growth factor (TGF)-beta1 gene -509C/T polymorphism and the susceptibility to primary nephrotic syndrome (PNS), and in particular to the severe degree of tubulointerstitial damage (TID) seen in Chinese.

METHODS

Ninety-eight PNS patients and 128 normal controls were studied. The extent of tubulointerstitial changes was evaluated and patients were divided into two groups according to the severe or mild degree of TID. The TGF-beta1gene -509C/T polymorphism was detected with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique, and the serum level of TGF-beta1 was determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

No statistical differences in genotype or allele frequency of the TGF-beta1 gene -509C/T were found between PNS and normal subjects. However, T allele and CT + T T genotype frequency were higher in the PNS with severe TID than the mild TID and controls. Additionally, the serum concentration of TGF-beta1 was significantly higher in the PNS with severe TID group than the other two groups and in the T T genotype individuals than the CC and CT genotype individuals. A logistic regression analysis demonstrated that TGF-beta1 gene -509C/T genotype was the risk factor of TID in PNS patients [OR (odd ratio) 2.34, confidence interval (CI) 0.98-3.46, p = 0.012]. CONCLUSION. TGF-beta1 gene -509C/T polymorphism was associated with severe TID. The higher value in serum concentration of TGF-beta1 was also associated with severe TID and the T T genotype/T allele. T allele gene might be the important risk factor for susceptibility.

Is typing for HLA class II alleles beneficial in Indian children with idiopathic nephrotic syndrome?

This study was conducted to test the hypothesis that analysis of HLA class II type alleles will give important information on the prognosis of NS in children. We prospectively studied 100 consecutive children with idiopathic nephrotic syndrome and 202 controls belonging to the same geoethnic background. Typing for HLA Class II alleles at DR and DQ locus was carried out by using SSP (sequence specific oligonucleotides based method). In our study children were more likely to have nephrotic syndrome if the allele DQ-beta1*020X was present as compared to controls. On the other hand, DR-beta1*1001, DR-beta1*130X and DQ-beta1*030X were significantly lower among patients and likely to be protective. On analysing the different steroid response categories, we observed that the allele DQ-beta1*020X was significantly higher in infrequent relapsers (IFR) with a high etiological fraction of 0.714. Children were more likely to be steroid resistant if the allele DR-beta1*150X was present and the etiological fraction was high (0.754). The allele DQ-beta1*030X was significantly lower in steroid resistant patients (p=0.019, RR=0.1819, 95% CI=0.04430-0.7471) and likely to be protective. On analysing the haplotype distribution, we observed that occurrence of DR-beta1*070X-DQ-beta1*020X haplotype was significantly more common among patients with steroid sensitive nephrotic syndrome (23.94%) as compared to controls (12.5%) (p=0.01). In the steroid resistant group we observed that the haplotype DR-beta1*150X-DQ-beta1*060X was significantly more frequent as compared to steroid sensitive patients as well as controls p=0.01. We conclude that HLA typing in Indian children with NS helps to predict relapse frequency and steroid resistance.

Idiopathic nephrotic syndrome in Polish children - its variants and associations with HLA

HLA-DR and HLA-DQ antigens were investigated in 127 Polish children with idiopathic nephrotic syndrome (INS) followed-up for the median time of 11 years (minimum 7 years). HLA typing was performed using the polymerase chain reaction sequence-specific oligonucleotide probing technique and the microlymphocytotoxicity test. Histopathologic INS categories and a response to therapy were analyzed according to particular HLA associations. The results were compared with 330 healthy individuals. In INS children, we observed an increased frequency of HLA-DR7, DR3/7, DQ2 and DQ8, whereas HLA-DR13, DR15, DQ5 and DQ6 were decreased. In minimal change nephrotic syndrome, a relationship with HLA-DR3, DR7, DR3/7 and DQ2 was found. Evolved from minimal changes, focal segmental glomerulosclerosis was associated with HLA-DR7, while primary focal segmental glomerulosclerosis with HLA-DR4 and DQ8. In steroid-dependence and secondary steroid-resistance, an increased frequency of HLA-DR3, DR7, DR3/7 and DQ2 was documented. In contrast, primary steroid-resistant nephrotic syndrome was associated with HLA-DR4 and DQ8. Steroid-dependent patients bearing HLA-DR3 achieved longer remissions after chlorambucil therapy compared with HLA-DR3-negative. In steroid-resistant focal segmental glomerulosclerosis, a reduced response to cyclosporine A was associated with HLA-DR4. Associations with HLA differentiate between pathoanatomic entities of INS and may influence a response to immunosuppressive therapy.