To understand the genetics of steroid-sensitive nephrotic syndrome (SSNS), we conducted a genome-wide association study in 987 childhood SSNS patients and 3,206 healthy controls with Japanese ancestry. Beyond known associations in the HLA-DR/DQ region, common variants in NPHS1-KIRREL2 (rs56117924, P[4.94E-20, odds ratio (OR) [1.90)

Background Immunization with various vaccines is considered desirable for children with idiopathic nephrotic syndrome (NS) because of their high risk of severe infections. Vaccinations may precipitate relapses of NS, but there is no available data regarding inactivated influenza (flu) virus vaccines. Methods We retrospectively reviewed the medical records of children with NS who had received flu vaccines between 2002 and 2015. The day of flu vaccination was defined as day 0, and the period between the pre-vaccination and the post-vaccination days was defined as − X to + Y. The risk ratios and their 95% confidence intervals for NS relapse rate were estimated by generalized estimating equation (GEE) Poisson regression. Results A total of 104 pediatric patients received 208 flu vaccines. The mean age at onset of NS was at 4.85 ± 3.87 years old. There were 261 NS relapses between days − 180 and + 180. Compared with the relapse rate in the − 180 to 0 interval (1.19 times/person-year), those in 0 to + 30 (1.23), + 31 to + 60 (1.58), + 61 to + 90 (1.41), + 91 to + 120 (1.41), and + 121 to + 180 (1.32) days groups were slightly increased, but without significance. Multivariate analysis using GEE Poisson regression also showed no significant increase in relapse rate in each day group compared with days − 180 to 0. Risk ratios for NS relapse were significantly higher in children who were treated with steroids at the first vaccination. Conclusions Our results suggest that flu vaccines should not be avoided in children with NS based on the potential for NS relapses. Electronic supplementary material The online version of this article (10.1007/s10157-020-01930-8) contains supplementary material, which is available to authorized users.

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Children with systemic lupus erythematosus (SLE) generally undergo a pretreatment kidney biopsy. However, some of these patients, especially those with antiphospholipid syndrome (APS), may experience serious coagulopathic complications. We report herein two cases of paediatric SLE with APS in which, despite normal blood test results, the disparate coagulopathic complications of haemorrhage and embolism developed following a kidney biopsy. Case 1 was, an 8-year-old male in whom, primary APS was initially diagnosed. Fourteen months later SLE was diagnosed. Based on a percutaneous kidney biopsy, International Society of Nephrology and the Renal Pathology Society (ISN/RPS) class III-A lupus nephritis was histologically diagnosed. On post-biopsy Day 9, a giant haematoma in the fascia of the left kidney developed and was accompanied by changes in the vital signs. Case 2, a 13-year-old male, initially received the diagnosis of SLE with APS and underwent two courses of pulse methylprednisolone therapy. His coagulation abnormalities improved, and a percutaneous needle kidney biopsy was performed, leading to the histological diagnosis of ISN/RPS class III-A lupus nephritis. Furthermore, thrombotic microangiopathy was also detected in the renal histopathology. On post biopsy Day 6, the patient experienced right leg pain. A contrast CT and lower extremity ultrasonography detected a massive deep vein thrombosis and partial left pulmonary artery thrombosis. A kidney biopsy in children with SLE and APS can cause lethal coagulopathic complications, and the risks to such patients should be weighed carefully before the procedure is performed.

Background Despite advances in non‐invasive vascular imaging, detection of renal artery stenosis via catheter angiography is the criterion standard for the diagnosis of renovascular hypertension (RVH). However, because of lack of evidence, the utility of various blood tests and imaging modalities remains unclear. Methods We retrospectively analyzed the utility of blood tests (plasma renin activity [PRA], aldosterone, and renal vein renin [RVR] values) and imaging studies (computed tomography angiography [CTA], kidney ultrasonography [US]) by comparing them with catheter angiography. Ten pediatric patients with RVH at two institutions from January 2008 to December 2017 were recruited. The sensitivities for diagnosing RVH via imaging and blood tests (kidney [US], PRA, and aldosterone) were derived by examining patient records. Furthermore, the sensitivity and specificity of CT angiography were calculated by considering both the affected and non‐affected renal arteries of the patients. Results A high sensitivity for diagnosing RVH via kidney US (89%) and PRA (80%) was observed. The sensitivity and specificity of CTA were 100%, each. RVR sampling did not aid in the diagnosis of RVH; only two of six patients with unilateral RVH showed significant laterality of RVR boundary ratios. Renal scintigraphy facilitated detection of a non‐functional kidney (split renal function <5%). Conclusions RVH in children could be diagnosed utilizing non‐invasive blood and imaging tests, without catheter angiography. We recommend kidney length measurement along with measurement of PRA level, as a simple and highly useful screening test, followed by CTA as a diagnostic test.