These results indicate that these disorders are difficult to distinguish in some patients, even when using diuretic challenge. This clinical report provides important findings that can improve our understanding of inherited salt-losing tubulopathies and renal tubular physiology.

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)

Recent advances in genetics have resulted in a better understanding of many human inherited diseases, but most of them are monogenic disorders and more complex inheritance patterns remain unresolved. Our case provides clear evidence of digenic inheritance outside the scope of Mendelian inheritance disorders.

Recent studies indicate that adding the mineralocorticoid receptor antagonist spironolactone (SP) to angiotensin converting enzyme inhibitors (ACEI) or ACEI and angiotensin receptor blocker (ARB), which is known as a triple blockade, enhances the more beneficial effects on urinary protein excretion of patients with chronic kidney diseases. In this study, we explored the effects of SP on urinary protein excretion in patients with Alport syndrome featuring persistent proteinuria in spite of the long-term use of ACEI (lisinopril) or both ACEI and ARB (candesartan). Five patients with Alport syndrome were enrolled and SP treatment (25 mg/day) was started. At the start of SP administration, all patients showed good renal function and none of them suffered from hypertension. We decided to assess the effect of SP by determining the morning urinary protein/creatinine ratio (U-P/C) and estimated glomerular filtration rate (EGFR). After SP treatment was started, U-P/C was significantly reduced at 3, 6, 12 and 18 months, while EGFR did not change. The drop in systolic and diastolic blood pressure was statistically significant and serum potassium level was slightly elevated. None of the patients showed signs of severe hyperkalemia (>5.0 mEq/l). These results suggest that aldosterone receptor blockade combined with ACEI and ARB therapy offers a valuable adjuvant treatment for the reduction of proteinuria in patients with Alport syndrome as in those with other chronic kidney diseases. SP can thus be expected to constitute a good renoprotective agent for Alport syndrome. These preliminary data indicate that large-scale trials of this therapy should be done.

The management of Henoch-Schönlein purpura nephritis (HSPN) is controversial. It has been revealed that some patients develop end-stage renal disease and aggressive treatment with drugs such as steroids is increasing, and some of them may be overzealous. At our institutes, our treatment decisions are based on the clinical and pathological severity of the case in an attempt to limit the indications for aggressive therapies such as steroids and immunosuppressive agents. Here, we retrospectively examined the efficacy of treatment for HSPN. Renal biopsy was performed in patients with nephrotic syndrome or persistent proteinuria for more than 3 months and patients were classified by treatment. Patients (n=31) with moderately severe HSPN (histological grade I-III and serum albumin [Alb] >2.5 g/dl) were treated with angiotensin-converting enzyme inhibitors and/or angiotensin receptor blockers. Patients (n=19) with HSPN exceeding grade III or Alb ≤ 2.5 g/dl received combination therapy comprising prednisolone, immunosuppressants, warfarin, and dipyridamole. All patients showed resolution of proteinuria without renal dysfunction during the observation period (3.76 ± 0.37 years). Our findings support those of some earlier reports that treatment strategies for HSPN should depend on the histological and clinical severity. Furthermore, aggressive therapies, particularly combination therapies, are unnecessary for moderate-severe HSPN.