Genetic Identification of Two Novel Loci Associated with Steroid-Sensitive Nephrotic Syndrome.

BACKGROUND: Steroid-sensitive nephrotic syndrome (SSNS), the most common form of nephrotic syndrome in childhood, is considered an autoimmune disease with an established classic HLA association. However, the precise etiology of the disease is unclear. In other autoimmune diseases, the identification of loci outside the classic HLA region by genome-wide association studies (GWAS) has provided critical insights into disease pathogenesis. Previously conducted GWAS of SSNS have not identified non-HLA loci achieving genome-wide significance. METHODS: In an attempt to identify additional loci associated with SSNS, we conducted a GWAS of a large cohort of European ancestry comprising 422 ethnically homogeneous pediatric patients and 5642 ethnically matched controls. RESULTS: The GWAS found three loci that achieved genome-wide significance, which explain approximately 14% of the genetic risk for SSNS. It confirmed the previously reported association with the HLA-DR/DQ region (lead single-nucleotide polymorphism [SNP] rs9273542, P=1.59×10-43; odds ratio [OR], 3.39; 95% confidence interval [95% CI], 2.86 to 4.03) and identified two additional loci outside the HLA region on chromosomes 4q13.3 and 6q22.1. The latter contains the calcium homeostasis modulator family member 6 gene CALHM6 (previously called FAM26F). CALHM6 is implicated in immune response modulation; the lead SNP (rs2637678, P=1.27×10-17; OR, 0.51; 95% CI, 0.44 to 0.60) exhibits strong expression quantitative trait loci effects, the risk allele being associated with lower lymphocytic expression of CALHM6. CONCLUSIONS: Because CALHM6 is implicated in regulating the immune response to infection, this may provide an explanation for the typical triggering of SSNS onset by infections. Our results suggest that a genetically conferred risk of immune dysregulation may be a key component in the pathogenesis of SSNS.

Combined liver and kidney transplantation in children: analysis of renal graft outcome.

BACKGROUND: Combined liver-kidney transplantation (CLKT) is the accepted treatment for patients with both liver failure and progressive renal insufficiency. Long-term outcome data for CLKT in children is sparse and controversy exists as to whether simultaneous CLKT with organs from the same donor confers immunologic and survival benefit to the kidney allograft. We report the long-term renal graft outcomes of 40 patients who had simultaneous CLKT. METHODS: A retrospective analysis of kidney graft survival (time from transplantation to death, return to dialysis or last follow-up event) in all pediatric patients (age < 18 years old) who underwent CLKT from March 1994 to January 2015. A 1:1 ratio of controls (deceased donor kidney recipients from our centre matched for age (±2 years) at transplant, time from transplant (±1 year) and treated with the same immunosuppressive regime) to cases was used to compare outcome. Estimated glomerular filtration rate (e-GFR) was calculated using the Schwartz formula. Survival curves were determined using Kaplan-Meier analysis. RESULTS: The kidney graft survival for CLKT patients was 87.4, 82, and 82 % at 1, 5, and 10 years; kidney graft survival for isolated KT patients were 97.2, 93, and 93 % at 1, 5, and 10 years (p = NS). There were two acute rejection episodes (5 %) in the CLKT group compared to five (12.5 %) episodes in the isolated KT group. There was no statistically significant difference in e-GFR at 1, 5, and 10 years in the two groups but there was a statistically significantly greater decline in e-GFR in the KT group compared to CLKT group from 5-10 years following transplant. CONCLUSIONS: There are fewer acute rejection episodes following CLKT compared to isolated KT, and we noted a higher mean e-GFR at 1, 5, and 10 years with significantly lesser decline in e-GFR from 5 to 10 years in the CLKT group.

Management strategies for common viral infections in pediatric renal transplant recipients.

Viral infections have been considered as a major cause of morbidity and mortality after kidney transplantation in pediatric cohort. Children are at high risk of acquiring virus-related complications due to immunological immaturity and the enhanced alloreactivity risk that led to maintenance of high immunosuppressive regimes. Hence, prevention, early detection, and prompt treatment of such infe ctions are of paramount importance. Among all viral infections, herpes viruses (herpes simplex virus, varicella zoster virus, Epstein-Barr virus, cytomegalovirus), hepatitis B and C viruses, BK polyomavirus, and respiratory viruses (respiratory syncytial virus, parainfluenza virus, influenza virus and adenovirus) are common in kidney transplant recipients. These viruses can cause systemic disease or allograft dysfunction affecting the clinical outcome. Recent advances in tech nology and antiviral therapy have improved management strategies in screening, monitoring, adoption of prophylactic or preemptive therapy and precise trea tment in the immunocompromised host, with significant impact on the outcome. This review discusses the etiology, screening and monitoring, diagnosis, pre vention, and treatment of common viral infections in pediatric renal transplant recipients.

Common Risk Variants in AHI1 Are Associated With Childhood Steroid Sensitive Nephrotic Syndrome.

Introduction: Steroid-sensitive nephrotic syndrome (SSNS) is the most common form of kidney disease in children worldwide. Genome-wide association studies (GWAS) have demonstrated the association of SSNS with genetic variation at HLA-DQ/DR and have identified several non-HLA loci that aid in further understanding of disease pathophysiology. We sought to identify additional genetic loci associated with SSNS in children of Sri Lankan and European ancestry. Methods: We conducted a GWAS in a cohort of Sri Lankan individuals comprising 420 pediatric patients with SSNS and 2339 genetic ancestry matched controls obtained from the UK Biobank. We then performed a transethnic meta-analysis with a previously reported European cohort of 422 pediatric patients and 5642 controls. Results: Our GWAS confirmed the previously reported association of SSNS with HLA-DR/DQ (rs9271602, P = 1.12 × 10-27, odds ratio [OR] = 2.75). Transethnic meta-analysis replicated these findings and identified a novel association at AHI1 (rs2746432, P = 2.79 × 10-8, OR = 1.37), which was also replicated in an independent South Asian cohort. AHI1 is implicated in ciliary protein transport and immune dysregulation, with rare variation in this gene contributing to Joubert syndrome type 3. Conclusions: Common variation in AHI1 confers risk of the development of SSNS in both Sri Lankan and European populations. The association with common variation in AHI1 further supports the role of immune dysregulation in the pathogenesis of SSNS and demonstrates that variation across the allele frequency spectrum in a gene can contribute to disparate monogenic and polygenic diseases.

Association between childhood constipation and exposure to stressful life events: a systematic review.

BACKGROUND: Several cross-sectional studies have reported an association between childhood constipation and exposure to stressful events. We planned to systematically review the literature on constipation and its associated stressful events. METHODS: PubMed, Embase, and PsycINFO databases were searched (until February 2021) using standard search terms related to "constipation" and "stress" from 0 to 18 years that describe the association between psychological stressors and constipation. Studies were screened using pre-designed eligibility criteria. Studies that fulfilled the criteria were reviewed in a full-text format. The quality assessment of selected articles was conducted using standard methods. KEY RESULTS: Of 2296 titles and abstracts screened, 38 were included in the full-text review. Out of that, 15 articles were included in this systematic review. There were 2954 children with constipation, and the age range was from 6 months to 16 years. Exposure to home-related stressors (divorce or separation of parents, severe illness in family, and parental job loss) school-related stressors (including being bullied at school, change in school, separation from the best friend at school, and failure in an examination), exposure to child maltreatments and exposure to war/civil unrest were associated with childhood constipation. CONCLUSIONS AND INFERENCES: Exposure to day-to-day home- and school-related stressors, to child maltreatment, and to civil unrest is associated with constipation in children and adolescents. These factors need to be explored during clinical evaluation of children with constipation.

Effect of Prior Symptomatic Dengue Infection on Dengue Haemorrhagic Fever (DHF) in Children.

Pathogenesis of dengue haemorrhagic fever is not fully understood, but it is thought that there is antibody enhancement during the secondary infection, which causes severe dengue haemorrhagic fever (DHF). Therefore, patients who have DHF should have a documented history of symptomatic dengue infection in the past. A retrospective descriptive-analytical study was conducted at the University Paediatric Unit at Lady Ridgeway Hospital for Children, Colombo, Sri Lanka. All children who had fulfilled the criteria for DHF admitted to the unit from April 2018 to September 2018 were recruited into the study. Relevant data were collected from bed head tickets. One hundred and eighty-four children were included in the final analysis. Thirty-three (17.9%) had a past history of documented symptomatic dengue infection, while 82.1% did not have a documented dengue infection. Twelve patients had dengue shock syndrome, and none of them had previously documented symptomatic dengue fever. Dextran was used in 96 patients in the critical phase. Twelve (42%) patients with past documented symptomatic dengue fever needed dextran while 84 (54.9%) patients without a documented past history of dengue fever needed dextran. In our clinical observation, we noticed that children with DHF mostly did not have a documented symptomatic prior dengue infection, while those with a documented symptomatic prior infection had a milder subsequent illness. In fact, the majority (82.1%) of patients with DHF did not have documented previous symptomatic dengue infection. It was also observed that the clinical course of subsequent dengue infection was less severe in patients with previously documented symptomatic dengue fever. This finding should be further evaluated in a larger scale study minimizing the all-confounding factors. This fact is more important in selecting recipients for vaccines against the dengue virus, which are supposed to produce immunity against the virus without causing the severe disease.

Combined liver and kidney transplantation in children and long-term outcome.

Combined liver-kidney transplantation (CLKT) is a rarely performed complex surgical procedure in children and involves transplantation of kidney and either whole or part of liver donated by the same individual (usually a cadaver) to the same recipient during a single surgical procedure. Most common indications for CLKT in children are autosomal recessive polycystic kidney disease and primary hyperoxaluria type 1. Atypical haemolytic uremic syndrome, methylmalonic academia, and conditions where liver and renal failure co-exists may be indications for CLKT. CLKT is often preferred over sequential liver-kidney transplantation due to immunoprotective effects of transplanted liver on renal allograft; however, liver survival has no significant impact. Since CLKT is a major surgical procedure which involves multiple and complex anastomosis surgeries, acute complications are not uncommon. Bleeding, thrombosis, haemodynamic instability, infections, acute cellular rejections, renal and liver dysfunction are acute complications. The long-term outlook is promising with over 80% 5-year survival rates among those children who survive the initial six-month postoperative period.

Severe Disfiguring Scalp and Facial Oedema due to Henoch-Schönlein Purpura in a Child.

Henoch-Schönlein purpura is a small vessel vasculitis that usually presents with palpable purpura, arthritis, abdominal pain, and nephritis. Subcutaneous oedema of dependent areas is common; however, oedema in the scalp is extremely rare especially in children older than two years. Here, we report a child with massive disfiguring scalp and facial oedema due to Henoch-Schönlein purpura. An eight-year-old boy presented with characteristic palpable purpuric rash and extensive disfiguring scalp and facial swelling for five days. He complained of blurred vision, vomiting, and severe headache on the day of admission. Examination revealed an ill child with extensive oedema of the face and scalp that was tender on palpation. His blood pressure was above the 99th percentile, and he had exaggerated deep tendon reflexes and extensor plantar responses. All biochemical investigations including renal function tests were normal. Noncontrast CT head showed normal brain, with marked soft tissue swelling of the scalp. Ultrasonography showed soft tissue oedema within and surrounding facial muscles without evidence of neck vessel compression. Urine analysis revealed microscopic haematuria on day 14 of the illness, and immunohistochemical staining of renal biopsy confirmed Henoch-Schönlein purpura nephritis. In conclusion, this case report presents a child with severe, disfiguring scalp and facial oedema due to Henoch-Schönlein purpura. It highlights that severe subcutaneous oedema of Henoch-Schönlein purpura can involve any part of the body not limiting to dependent areas.

A child with distal (type 1) renal tubular acidosis presenting with progressive gross motor developmental regression and acute paralysis.

BACKGROUND: Distal (Type 1) renal tubular acidosis (dRTA) is characterized by inability to secrete hydrogen irons from the distal tubule. The aetiology of dRTA is diverse and can be either inherited or acquired. Common clinical presentations of dRTA in the paediatric age group include polyuria, nocturia, failure to thrive, constipation, abnormal breathing and nephrolithiasis. Though persistent hypokalemia is frequently seen in dRTA, hypokalemic muscular paralysis is uncommon and rarely described in children. CASE PRESENTATION: Three and a half years old girl was referred for evaluation of progressive loss of gross motor milestones over 6 months and acute episode of paralysis. Her other developmental domains were age appropriate. Notably, there was no history of polyuria, polydipsia, nocturia and abnormal breathing. Physical examination revealed proximal myopathy (waddling gait and positive Gower's sign), diminished lower limb reflexes and muscle tone. Her serum potassium was low (2.1 meq/l) and she was subsequently investigated for hypokalemic paralysis. Diagnosis of distal renal tubular acidosis was made, based on hypokalemic hyperchloremic metabolic acidosis with normal anion gap, high urine pH, borderline hypercalciuria, medullary nephrocalcinosis and exclusion of other differential diagnosis. The child showed complete symptomatic recovery upon commencement of standard treatment for distal renal tubular acidosis. CONCLUSIONS: This case report highlights the importance of considering hypokalemia and renal tubular acidosis in the differential diagnosis of acute flaccid paralysis and proximal myopathy. Early diagnosis will prevent costly investigations and enable rapid clinical recovery in the affected child.

The first Sri Lankan family with Dent disease-1 due to a pathogenic variant in the CLCN5 gene: a case report.

BACKGROUND: Dent disease-1 is a rare X-linked recessive renal tubular disorder caused by pathogenic variants in the chloride voltage-gated channel 5 (CLCN5) gene. It is characterized by low-molecular-weight proteinuria, hypercalciuria, nephrocalcinosis, nephrolithiasis and progressive renal failure. This is the first report of a CLCN5 pathogenic variant in a Dent disease-1 family of Sri Lankan origin, and it highlights the value of genetic evaluation in children with refractory proteinuria. CASE PRESENTATION: A 2-year-old boy with non-nephrotic range proteinuria was referred for evaluation. His maternally related 24-year-old uncle had been investigated for similar features at the age of 14 years and his renal histology had shown few sclerosed glomeruli. He remained asymptomatic apart from proteinuria. Biochemical investigation of the child showed ß-2 microglobulinuria and hypercalciuria. After providing pre-test counseling and obtaining written informed consent, the child, his mother and maternal uncle underwent genetic testing for confirmation of the clinically suspected diagnosis of Dent disease-1. Both the child and his maternal uncle were found to be hemizygous for a nonsense pathogenic variant in exon 9 of the CLCN5 gene [NM_000084.4; c.1399C>T; rs797044811] which results in a stop codon at residue 467, leading to a truncated non-functional protein [NP_000075.1; p.R467X]. His mother was confirmed to be an unaffected heterozygous carrier for the same variant. Following confirmation of the diagnosis our patient was started on thiazide diuretics and potassium citrate. CONCLUSIONS: Even though the typical phenotype of Dent disease-1 often enables a clinical diagnosis to be made, less severe sub-clinical cases may go undiagnosed. The underlying diagnosis may be missed especially in children who are treated for non-minimal change nephrotic syndrome with steroids. This case highlights the need for tubular proteinuria to be considered in the differential diagnosis of children with refractory proteinuria and for appropriate genetic evaluation to be done to confirm the precise underlying diagnosis in such cases.