A case of Dent disease type 2 with large deletion of OCRL diagnosed after close examination of a school urinary test.

A 7-year-old boy visited our hospital for a detailed examination of proteinuria identified in a school urinary test. He had short stature, misaligned teeth, and mild intellectual disability. A urinary examination identified mild proteinuria and extremely high levels of beta-2 microglobulin. On blood examination, his protein, albumin, and creatinine levels were found to be normal; however, his lactate dehydrogenase and creatinine phosphokinase levels were slightly elevated. Upon histological examination, no abnormalities in glomeruli or tubules were found. Considering these results, we diagnosed our patient with Dent disease type 2 (DD2). Although the whole exome sequencing revealed large deletion of OCRL, which was seen only in Lowe syndrome and not in DD2 previously, our final diagnosis for the patient is DD2. A phenotypic continuum exists between Dent disease and Lowe syndrome, and several factors modify the phenotypes caused by defects in OCRL. Although patients have thus far been diagnosed with DD2 or Lowe syndrome on the basis of their symptoms, accumulation and analysis of cases with OCRL defects may hereafter enable more accurate diagnoses.

Association between Immunoglobulin M and Steroid Resistance in Children with Nephrotic Syndrome: A Retrospective Multicenter Study in Japan.

Background: The prognosis of steroid-resistant nephrotic syndrome (SRNS) in children is poorer than steroid-sensitive cases. Diagnosis of SRNS is made after observing the response to the initial 4-week corticosteroid therapy, which might be accompanied by side effects. However, predictive indicators at initial diagnosis remain unknown. We aimed to investigate whether selectivity index (SI) and other indicators at initial diagnosis-for example, serum IgM and total serum protein-albumin ratio (TA ratio, total serum protein level over albumin level)-can predict SRNS. Methods: A total of 80 children were enrolled from seven hospitals in Japan between January 2008 and December 2019 (mean age, 4.7 years; 65% male). Of the children enrolled, 13 (16%, M/F=5:8) had been diagnosed as steroid resistant after initial treatment with steroids. The association between serum IgM (tertile categories: low, 24-133; middle, 134-169; and high, 169.1-510 mg/dl), SI (<0.2 or ≥0.2), and TA ratio (tertile categories: low, 1.8-2.6; middle, 2.62-3.75; and high, 3.8-15.3) at initial diagnosis and steroid resistance was evaluated with logistic regression, adjusting for age and sex. Results: Low levels of serum IgM were significantly associated with steroid resistance (adjusted odds ratio, 6.94; 95% CI, 1.12 to 43.11). TA ratio and SI were not significantly associated with steroid resistance. Conclusions: Low levels of serum IgM at initial diagnosis might predict steroid resistance among Japanese children with idiopathic nephrotic syndrome.

Successful Long-term Graft Survival of a Renal Transplantation Patient with Wiskott-Aldrich Syndrome.

Wiskott-Aldrich syndrome, a rare X-linked hereditary syndrome, is characterized by immunodeficiency, thrombocytopenia, and eczema. The underlying T-cell defect renders renal transplantation and immunosuppressive treatments uncertain. The present case exhibited the mild clinical manifestation, regarded as X-linked thrombocytopenia. He successfully underwent a living-donor ABO-compatible renal transplantation and splenectomy in 2002, and thereafter experiencing no severe rejection, serious infection, or malignancy for more than 10 years. Though IgA nephropathy was detected 8 months after transplantation, the patient's renal function and proteinuria were stable without any treatment. The present case showed a successful long-term graft survival and the importance of splenectomy added to renal transplantation.

Efficacy and safety of eculizumab in childhood atypical hemolytic uremic syndrome in Japan.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a severe life-threatening disease with frequent progression to end-stage renal disease (ESRD). Eculizumab, a humanized anti-C5 monoclonal antibody targeting the activated complement pathway, has recently been introduced as a novel therapy against aHUS. We, therefore, investigated the efficacy and safety of eculizumab in Japanese pediatric patients. METHODS: We retrospectively analyzed clinical course and laboratory data of the first ten children with aHUS treated with eculizumab nationwide. RESULTS: Seven patients were resistant to plasma therapy and three were dependent on it. Causative gene mutations were found in five patients. Two patients had anti-complement factor H autoantibody. Three patients had a family history of thrombotic microangiopathy (TMA). After initiation of eculizumab, all patients immediately achieved hematological remission and could successfully discontinue plasma therapy. The median periods to normalization of platelet count, lactate dehydrogenase levels and disappearance of schistocytes were 5.5, 17 and 12 days, respectively. Nine patients recovered their renal function and the median period to terminate renal replacement therapy (RRT) was 3 days. However, two patients progressed to ESRD and required chronic RRT at the last observation. No patients had a relapse of TMA under regular eculizumab therapy. No serious adverse events occurred during the follow-up period. CONCLUSIONS: Eculizumab is efficacious and well-tolerated therapy for children with aHUS. Although pathogenic mutations could not be detected in five patients, all patients showed immediate normalization of hematological abnormalities, strongly suggesting complement-related aHUS. This prompt hematological amelioration can become an indicator for therapeutic efficacy of eculizumab. However, appropriate indications and optimal duration of the treatment remain unclear.

[Case of a 14-year-old boy with chronic tubulointerstitial nephritis first diagnosed as acute focal bacterial nephritis].

A 14-year-old boy was admitted to a general hospital because of prolonged fever of unknown origin. After Enterococcus feacalis was detected from his urine and abdominal contrast enhanced computed tomography and 99m-Tc dimercaptosuccinic acid scintigram showed multiple focal defects, he was diagnosed as acute focal bacterial nephritis (AFBN). His condition recovered as a result of Ampicillin (ABPC)and Cefotaxime infusion. There was no specific finding in voiding cystography. Six months later, his fever recurred and he was diagnosed as refractory AFBN because Enterococcus feacalis was detected in his urine again. He was treated with ABPC and Meropenem (MEPM) infusion, but the fever persisted and his renal function deteriorated. He was transferred to our hospital for intensive treatment. On admission, blood examination showed findings of inflammation (WBC 14,400/µL, CRP 3.7 mg/dL, erythrocyte sedimentation rate : 69 mm/h, IgG : 2,107 mg/dL) and renal impairment (Cr : 1.8 mg/dL, cystatin C : 2.0 mg/L). Although neither pyuria nor pathogenic bacteria were detected in his urine, Enterococcusfeacalis was detected at the hospital where he had been treated previously, hence we started treatment for AFBN with ABPC, MEPM, Levofloxacin, then Linezolid. However, the fever persisted and his renal function deteriorated (Cr 2.0 mg/dL). Kidney-specific accumulation was found in Ga scintigraphy, which suggested chronic inflammation. Clinical course and laboratory findings showed no symptoms of bacterial, viral, fungal, or tuberculous infections nor collagen disease. Although renal biopsy revealed no glomerular abnormality, tubulointerstitial edema, fibrosis and tubulitis were observed. Rupture of the tubular basal membrane and non-caseating granulomas also existed. Pathological findings did not match those of renal sarcoidosis. Ophthalmological screening negated the existence of tubulointerstitial nephritis with uveitis syndrome. After methylprednisolone pulse therapy, the fever recovered immediately and his renal impairment imroved gradually (Cr 1.49 mg/dL). He continues to undergo treatment as an outpatient. Although tubulointerstitial nephritis is rare in children, some patients have a poor renal prognosis. It is important to determine the existence of tubulointerstitial nephritis on treating a patient with renal impairment.

Graft versus host disease-dependent renal dysfunction after hematopoietic stem cell transplantation.

Nephropathy is an important complication in hematopoietic stem cell transplantation (HSCT) wherein multifactorial causes, i.e., radiation, drug toxicity, graft versus host disease (GVHD), are thought to contribute renal dysfunction. Here, we report a 10-year-old boy with high-risk acute myelocytic leukemia and severe but partially reversible renal dysfunction. The patient initially received umbilical cord blood transplantation (UCBT) with CY 120 mg/kg and kidney unshielded 12 Gy of total body irradiation. After the leukemic relapse, he received allogenic bone marrow transplantation (BMT) 270 days after the first transplantation. Two months later, his renal function started to deteriorate and urinary protein increased gradually to 1 g/day. Four months after BMT, by the symptoms of severe GVHD, the dose of tacrolimus, utilized to avoid GVHD, was increased although his serum Cre level elevated to 2.97 mg/dL. Serum Cre level improved to 2.0 mg/dL paralleled with GVHD improvement. Renal histological findings showed severe interstitial edema, features of thrombotic microangiopathy (TMA), and C4d deposition along the glomerular capillaries and peritubular capillaries. We suggested that control of GVHD had benefitted to ameliorate renal function of the patient. Treatment for GVHD improved renal dysfunction and TMA of our patients. Moreover, renal biopsy was powerful to elucidate the exact origin of renal dysfunction after HSCT.

Effect of eculizumab and recombinant human soluble thrombomodulin combination therapy in a 7-year-old girl with atypical hemolytic uremic syndrome due to anti-factor H autoantibodies.

Atypical hemolytic uremic syndrome (aHUS), which is defined as non-Shiga toxin-associated hemolytic uremic syndrome, is a type of thrombotic microangiopathy. This syndrome presents with hemolytic anemia, thrombocytopenia, and acute kidney injury. Excessive complement activation due to genetic disorders of the complement system or production of autoantibodies to factor H (FH) causes the disease. We report a successful treatment course using eculizumab and recombinant human soluble thrombomodulin (rTMD) for a 7-year-old girl with aHUS due to anti-FH autoantibodies. Although her chief complaints were abdominal pain and loose stools, we were finally able to diagnose her with aHUS because Shiga toxin-producing Escherichia coli was not detected in her feces and a hemolytic assay analyzing FH function was positive. We administrated rTMD to our patient because of signs of disseminated intravascular coagulation. Soon after the therapeutic intervention, the platelet count began to increase and abdominal pain was moderately improved. Plasma exchange limited the efficacy of her disease. Therefore, we administered eculizumab, monoclonal humanized antibody against C5, 3 weeks after admission. Platelet counts immediately increased and kidney function gradually recovered. Genetic disorders were not detected. However, anti-FH autoantibody was observed. There were no symptoms for recurrence of aHUS or kidney dysfunction for 15 months, as a result of the administration of eculizumab every other week. In conclusion, combination therapy of eculizumab and rTMD was effective for an aHUS patient. This therapy may be helpful for improving the prognosis and long-term kidney function of aHUS patients.

Megalin contributes to the early injury of proximal tubule cells during nonselective proteinuria.

Megalin, a member of the LDL receptor family, is expressed on the apical membrane of proximal tubules and serves as an endocytic scavenger of filtered proteins and hence might contribute to the tubule injury as a consequence of glomerular disease. To study its role, we crossed megalin knockout mosaic mice (lacking megalin expression in 60% of proximal tubule cells) with NEP25 mice (a transgenic line expressing human CD25 in the podocyte). Treatment of this transgenic mouse with the immunotoxin causes nephrotic syndrome, focal segmental glomerulosclerosis and tubule-interstitial injury. Following this treatment, the double transgenic mice had massive non-selective proteinuria and mild glomerular and tubular injury. Comparison of megalin-containing to megalin-deficient proximal tubule cells within each kidney showed that albumin, immunoglobulin light chain, IgA and IgG were preferentially accumulated in proximal tubule cells expressing megalin. Tubule injury markers such as heme-oxygenase-1, monocyte chemoattractant protein-1 and cellular apoptosis were also preferentially found in these megalin-expressing cells. These results show that megalin plays a pivotal role in the reabsorption of small to large molecular size proteins and provides direct in vivo evidence that reabsorption of filtered proteins triggers events leading to tubule injury.

Calcium oxalate saturation in dialysis patients with and without primary hyperoxaluria.

Calcium oxalate supersaturation of the blood is associated with deposition of crystals in various tissues. We measured the serum levels of oxalate, citrate, calcium, and magnesium to estimate their saturation in 112 hemodialysis patients without primary hyperoxaluria and two boys with primary hyperoxaluria. Serum levels of oxalate and citrate were determined by high-performance capillary electrophoresis, while calcium and magnesium were measured by ICP spectroscopy. The serum levels of oxalate, citrate, calcium, and magnesium were 44.9+/-16.5, 138.1+/-54.9 micromol/l, 2.30+/-0.28, and 1.07+/-0.18 mmol/l, respectively, while the levels in patients with primary hyperoxaluria were 83.9+/-34.3, 197.9+/-63.5 micromol/l, 2.53+/-0.15, and 1.14+/-0.34 mmol/l, respectively. Serum calcium oxalate saturation (SS), as calculated by the Equil program, was significantly correlated with the serum oxalate level. Most patients showed metastable supersaturation (1