Thrombotic Microangiopathy, Podocytopathy, and Damage to the Renal Tubules with Severe Proteinuria and Acute Renal Dysfunction Induced by Lenvatinib.

Lenvatinib, a tyrosine kinase inhibitor (TKI), is a stronger inhibitor of vascular endothelial growth factor receptor, fibroblast growth factor receptors 1 to 4, and platelet-derived growth factor receptor (PDGFR) than other TKIs. We herein report a 77-year-old Japanese woman who received the minimum dose of lenvatinib for treatment of hepatocellular carcinoma. Within one month of starting treatment, she developed severe proteinuria, hypertension, and renal dysfunction. A kidney biopsy showed drug-induced thrombotic microangiopathy, podocytopathy, and polar vasculosis. We also observed damage to the renal tubules, where PDGFR is located. To our knowledge, this is the first report of lenvatinib-induced damage to the renal tubules.

A case of thrombotic microangiopathy associated with polymyositis.

A 60-year-old Japanese woman with polymyositis (PM) developed hemolytic anemia (hemoglobin of 7.3 g/dL), thrombocytopenia (platelet of 9.1×104/µL), and acute kidney injury (Cre of 4.7 mg/dL) at 14 days after starting steroid therapy. Renal biopsy revealed glomerular endothelial swelling with fibrin thrombi and fragmented erythrocytes in the capillary lumens. Hemolytic uremic syndrome (HUS) with thrombotic microangiopathy (TMA) was diagnosed. Hemodialysis and plasma exchange/plasma transfusion were initiated, but HUS did not subside. After 45 days, the patient died of hemorrhagic respiratory failure. Autopsy showed fibrin thrombi filling the glomerular vascular pole and the small arteries in most glomeruli, resulting in glomerular collapse and glomerular basement membrane (GBM) duplication. Although renal involvement by PM is rare, HUS/TMA should be remembered as one of the serious renal complications of PM.

Dialysis-related amyloidosis associated with a novel ß2-microglobulin variant.

Till date, there had been no reported case of dialysis-related amyloidosis (DRA) associated with a ß2-microglobulin variant. We report here a 41-year-old haemodialysis patient with systemic amyloidosis, exhibiting macroglossia and swelling salivary glands, uncommon clinical manifestations for DRA. Molecular analysis showed that the patient had a new variant of ß2-microglobulin (V27M). Extracted amyloid protein was predominantly composed of variant ß2-microglobulin. In vitro analysis revealed that this variant ß2-microglobulin had a strong amyloidogenic propensity, probably owing to the decreased stability caused by a bulky methionine residue. Our data clearly show that V27M variant is amyloidogenic and this mutation results in unusual clinical manifestations. To date, only one amyloidogenic ß2-microglobulin variant (D76N) has been reported in non-dialysis patients. It is noteworthy that the V27M and D76N variants show substantial differences in both clinical phenotypes and pathomechanical features. This is the first case of DRA associated with a naturally occurring ß2-microglobulin variant.

Glycated albumin and hemoglobin A1c levels and cause-specific mortality by patients' conditions among hemodialysis patients with diabetes: a 3-year nationwide cohort study.

INTRODUCTION: Differences in mortality and cause-specific mortality rates according to glycated albumin (GA) and hemoglobin A1c (HbA1c) levels among dialysis patients with diabetes based on hypoglycemic agent use and malnutrition status remain unclear. Here, we examine these associations using a nationwide cohort. RESEARCH DESIGN AND METHODS: We examined 40 417 dialysis patients with diabetes who met our inclusion criteria (female, 30.8%; mean age, 67.3±11.2 years; mean dialysis duration, 5.4±4.6 years). The Global Leadership Initiative on Malnutrition criteria were used to assess malnutrition. Adjusted HRs and 95% confidence limits were calculated for 3-year mortality after adjustment for 18 potential confounders. HRs and subdistribution HRs were used to explore cause-specific mortality. RESULTS: We found a linear association between 3-year mortality and GA levels only in patients with GA ≥18% and not in patients with low GA levels, with a U-shaped association between HbA1c levels and the lowest morality at an HbA1c 6.0%-6.3%. This association differed based on patient conditions and hypoglycemic agent use. If patients using hypoglycemic agents were malnourished, mortality was increased with GA ≥24% and HbA1c ≥8%. In addition, patients with GA ≥22% and HbA1c ≥7.6% had significantly higher infectious or cardiovascular mortality rates. On the other hand, an inverse association was found between GA or HbA1c levels and cancer mortality. Patients with GA ≤15.8% had a higher risk of cancer mortality, especially those not using hypoglycemic agents (HR 1.63 (1.00-2.66)). CONCLUSIONS: Target GA and HbA1c levels in dialysis patients may differ according to hypoglycemic agent use, nutritional status, and the presence of cancer. The levels may be higher in malnourished patients than in other patients, and a very low GA level in dialysis patients not taking hypoglycemic agents may be associated with a risk of cancer. TRIAL REGISTRATION NUMBER: UMIN000018641.

Genetics May Predict Effectiveness of Tolvaptan in Autosomal Dominant Polycystic Kidney Disease.

BACKGROUND: Tolvaptan is the only therapeutic drug for autosomal dominant polycystic kidney disease (ADPKD). The influence of mutations in polycystic kidney disease 1 and 2 genes (PKD1 and PKD2) on the treatment effects of tolvaptan is not well documented in the literature. METHODS: We retrospectively evaluated the relationship between genotype and the efficacy of tolvaptan in 18 patients with ADPKD who had been treated at Toranomon Hospital and undergone genetic testing between April 2016 and February 2020. RESULTS: The annual change in estimated glomerular filtration rate (ΔeGFR/y) from before to after tolvaptan was from a median of -5.5 to -2.5 mL/min/1.73 m2 in the PKD1 truncating group, -3.3 to -2.4 mL/min/1.73 m2 in the PKD1 non-truncating group, -3.1 to -1.6 mL/min/1.73 m2 in the PKD2 group, and -1.9 to -2.6 mL/min/1.73 m2 in the group with no PKD1/2 mutation. The median degrees of improvement of ΔeGFR/y were 2.5 (45%), 0.4 (10%), 0.6 (28%), and -0.7 (-37%) mL/min/1.73 m2, respectively. Compared with the group of patients with any PKD1/2 mutation, the group with no PKD1/2 mutation showed significantly less improvement in ΔeGFR/y with tolvaptan (0.6 vs. -0.7 mL/min/1.73 m2, respectively; p = 0.01) and significantly less improvement in the annual rate of increase in total kidney volume (TKV) with tolvaptan (-6.7 vs. -1.1%, respectively; p = 0.02). CONCLUSION: Patients with ADPKD and no PKD1/2 mutation showed less improvement in ΔeGFR/y and the annual rate of increase in TKV with tolvaptan. Detecting PKD1/2 mutations may be useful for predicting the effectiveness of tolvaptan.

The Clinical and Histopathological Feature of Renal Manifestation of TAFRO Syndrome.

INTRODUCTION: Thrombocytopenia, anasarca, myelofibrosis, renal dysfunction, and organomegaly (TAFRO) syndrome is a severe subtype of idiopathic multicentric Castleman's disease, characterized by thrombocytopenia, anasarca, fever, reticulin myelofibrosis, and organomegaly. Renal complication of this disease can be life-threatening and sometimes requires hemodialysis, but it has not been elucidated in detail. METHODS: Case-series was designed to evaluate the renal histology of patients with TAFRO syndrome treated at our hospital. RESULTS: Seven patients were eligible to the criteria. All of them had severe diuretic-resistant anasarca and 6 of 7 had mild proteinuria (<1 g daily). On light microscopy, all patients showed glomerular endotheliopathy characterized by endothelial cell swelling and a double contour of the glomerular basement membrane with mesangiolysis or mesangial loosening. Immunofluorescent staining and electron microscopy did not detect immune deposits in any patient. Electron microscopy revealed endothelial cell swelling with diffuse expansion of the subendothelial space, loss of mesangial architecture, and loss of endothelial cell fenestrations. Treatment with glucocorticoids and molecular-targeting agents, including tocilizumab and rituximab, improved renal dysfunction and anasarca. In 4 of 7 patients with persistent thrombocytopenia, hemorrhagic events occurred despite platelet transfusion or thrombopoietin receptor antagonist therapy. CONCLUSION: Severe diuretic-resistant anasarca with mild proteinuria and severe glomerular endotheliopathy were common characteristics of renal dysfunction due to TAFRO syndrome. In addition, endothelial changes mediated via interleukin (IL)-6 and vascular endothelial growth factor (VEGF) that lead to vascular hyperpermeability and water leakage might contribute to anasarca, because molecular-targeting therapy directed against IL-6 or VEGF improved renal dysfunction and severe endothelial damage.

Characteristic Renal Histology of a 81-Year-Old Patient with a 30-Year History of Diabetes Mellitus: A Case Report.

A renal histology of an 81-year-old man with a 30-year history of diabetes mellitus (DM), as well as diabetic retinopathy and neuropathy, was examined. The patient's blood pressure was controlled within the normal range (less than 140/75 mmHg) using antihypertensive agents including angiotensin receptor blocker. Edematous management was achieved by a strict salt diet (less than 6 g/per day). However, this patient's glycemic control was poor with HbA1c 8-10%. Serum creatinine was 0.87 mg/dL and estimated globular filtration rate (eGFR) was 64 ml/min/1.73m2. Urinary protein excretion was 1.5 g/day. This patient's renal biopsy showed linear staining for IgG along the GBM by immunofluorescence microscopy, but light microscopy showed almost intact glomeruli, and the GBM was not thickened as revealed by electron microscopy with a width of 288-368 nm (< 430 nm). While arteriolar hyalinosis was severe, and polar vasculosis was observed around the glomerular vascular pole. This case indicates that long-standing hyperglycemia may induce polar vasculosis by the mechanism of angiogenesis, but diabetic glomerulopathy can become minor change, only when hypertension and edematous management could be controlled strictly.

Candida albicans and Staphylococcus lugdunensis superinfection of liver cysts in a patient with autosomal dominant polycystic kidney disease under prednisolone treatment.

We report a case of superinfection of liver cysts caused by Candida albicans and Staphylococcus lugdunensis in a patient with autosomal dominant polycystic kidney disease. A 69-year-old man with chief complaints of headache and blurred vision was admitted to the former institution for the evaluation of suspected temporal arteritis. He was prescribed oral prednisolone (55 mg/day) as a preemptive treatment; however, he became febrile and presented with bilateral flank pain during prednisolone tapering. Blood culture revealed fungemia as a result of Candida famata infection; thus, micafungin treatment was started. Thereafter, recrudescence of the C-reactive protein level ensued. Then a cyst infection as visualized on magnetic resonance imaging led to cyst aspiration sclerotherapy. Cyst aspirate culture revealed the presence of C. albicans in one of the cysts and S. lugdunensis in two of the cysts. The patient was clinically stabilized with an additional 3 weeks of antibiotic and antifungal drug administration.

Denosumab for dialysis patients with osteoporosis: A cohort study.

Evidence for the efficacy of denosumab in HD patients is limited. Accordingly, here we report a study on the safety and efficacy of denosumab in these patients. We prospectively followed 324 patients (121 HD and 203 non-HD patients) receiving denosumab between June 2013 and May 2018, assessing changes in bone mineral density (BMD) and bone metabolic markers, and noting side-effects. Annual changes in BMD at the lumbar spine in HD and non-HD patients from baseline were, respectively, 6.7 ± 11.1% and 7.5 ± 10.2% (p = 0.60), those at the femoral neck were 4.3 ± 7.9% and 3.1 ± 9.5% (p = 0.32), and those at the distal radius were -0.5 ± 6.4% and 0.2 ± 13.0% (p = 0.66). The prevalence of hypocalcemia (<8.5 mg/dL) was significantly higher in HD than in non-HD patients (35.6% vs 5.4%, p < 0.001). The median elapsed time between the first injection of denosumab and the occurrence of hypocalcemia was 7 days in HD patients. The decrease of serum calcium was greater in patients with higher TRACP5b, corticosteroid use, and those without CaCO3 supplementation. Our study suggests that denosumab was equally as effective in HD as non-HD patients. However, careful hypocalcemia monitoring, for at least 4 weeks, is recommended for HD patients.

Corticosteroid reduction by addition of cetirizine and montelukast in biopsy-proven minimal-change nephrotic syndrome concomitant with allergic disorders.

Recent reports suggest helper T-cell abnormalities in minimal-change nephrotic syndrome (MCNS), which often complicate allergic disorders that show a similar helper T-cell profile with Th2/Th17 predominance. However, the effect of anti-allergy therapy on MCNS remains unknown. This retrospective study included 51 patients with biopsy-proven MCNS recruited between November 2012 and October 2015, with follow-up through November 2017. We analyzed relapse and temporal daily corticosteroid dose with and without co-administration of histamine H1 receptor antagonist, cetirizine, and cysteinyl-leukotriene receptor antagonist, montelukast, as well as between baseline and after follow-up. Thirteen patients were treated with cetirizine and montelukast in addition to conventional therapy, whereas 38 patients were treated by conventional therapy only, consisting of corticosteroids and immunosuppressants. To adjust for baseline clinical characteristics, a 1:1 propensity score-matched model was applied. The clinical characteristics of the two groups after matching were similar at baseline. The treatment group showed a significant reduction in the lowest daily dose of oral prednisolone throughout the entire treatment course after the study compared to that of baseline (p < 0.025), which was not observed in the control group (p = 0.37), and showed significantly higher percentage of patients establishing corticosteroid-free state for the first time throughout the entire treatment course by addition of cetirizine and montelukast compared to the control group (p < 0.025). The study shows, for the first time, the steroid sparing effect of cetirizine and montelukast in addition to conventional treatment in MCNS patients with concomitant allergies.

Regression of renal amyloid deposits by VAD therapy plus autologous stem cell transplantation in a patient with primary AL amyloidosis.

We report a 58-year-old Japanese woman who presented with nephrotic syndrome. Steroid therapy and cyclosporine A administration were initiated, but hematological remission and renal response were not achieved. Renal biopsy revealed amyloid deposits in the mesangial region and the small arteries. Proteomic analysis based on laser microdissection and mass spectrometry showed that the amyloid deposits were composed of the constant region of the lambda light chain. She received vincristine, adriamycin, and dexamethasone therapy followed by high-dose melphalan and autologous stem cell transplantation, resulting in hematological complete remission and renal response with negative urinary Bence-Jones protein and proteinuria. Renal biopsy was performed four times during follow-up, demonstrating that amyloid deposits decreased gradually, while glomeruli showing global sclerosis increased from 3 to 62%. This case suggests that glomerular amyloid deposits can be cleared via tissue remodeling, if stem cells producing amyloid precursors are completely replaced by unrelated cells after stem cell transplantation.

Efficacy of Secukinumab for Plaque Psoriasis in a Patient on Hemodialysis.

Secukinumab is effective to treat plaque psoriasis. However, the safety and efficiency of secukinumab have not been clarified in patients on hemodialysis. We report a 60-year-old Japanese woman. Plaque psoriasis was diagnosed at the age of 25 years and hemodialysis was started at the age of 39 years. Her skin lesions persisted despite use of topical agents such as maxacalcitol and betamethasone. Accordingly, administration of secukinumab was started at a dose of 150 mg. The psoriasis area and severity index (PASI) score decreased from 49.8 to 14.8 after 2 weeks and to 0 after 6 weeks, with remission being maintained after 28 months. No adverse reactions were seen. This case indicates that secukinumab may be effective for severe psoriasis in patients on hemodialysis for end-stage renal disease.

PKD1-associated autosomal dominant polycystic kidney disease with glomerular cysts presenting with nephrotic syndrome caused by focal segmental glomerulosclerosis.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) may manifest non-nephrotic range proteinuria, but is rarely complicated with nephrotic syndrome. Limited number of reports describe the histology of ADPKD with nephrotic syndrome in detail. CASE PRESENTATION: We encountered a 23-year-old man with polycystic kidney disease (PKD) with small kidney volume and nephrotic syndrome, which eventually progressed to end-stage renal disease. Renal histology showed typical focal segmental glomerulosclerosis and remarkable glomerular cyst formation, but did not reveal tubular cysts. PKD1 mutation was detected in him and his father, who also had PKD with small kidney volume. CONCLUSIONS: In contrast to tubular cysts which develop along ADPKD progression, glomerular cysts may likely be associated with ADPKD with slower volume progression manifesting small kidney volume. Although previous investigations report that ADPKD with smaller kidney volume is attributed to slower decline in renal function, coexistence of nephrotic-range proteinuria implies complication of other glomerular diseases and needs histological evaluation since it may lead to poor renal outcome.

Significance of urinary albumin excretion in patients with cast nephropathy
.

BACKGROUND: This study was performed to determine whether the urinary albumin excretion rate (%UAE) could distinguish myeloma cast nephropathy (MCN) without glomerular amyloid deposition from MCN with glomerular amyloid deposition. MATERIALS AND METHODS: We retrospectively reviewed clinicopathological data on 16 patients with MCN diagnosed by renal biopsy at Toranomon Hospital from 2004 to 2014. RESULTS: A total of 10 patients had pure MCN without glomerular amyloid deposition (group 1), and 6 patients had MCN with glomerular amyloid deposition (group 2). In all 10 patients from group 1, the underlying disease was multiple myeloma (MM), while 4 patients had MM, and 2 patients had lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM) in group 2. Total protein did not show a significant difference between the two groups, but serum albumin was significantly higher in group 1 than group 2 (p = 0.0101). Serum-adjusted calcium did not show a significant difference between the groups, while serum creatinine (Cre) was significantly higher in group 1 than group 2 (p = 0.0343). Although urinary protein excretion did not differ significantly between the groups, the %UAE was significantly lower in group 1 than group 2 (p = 0.00198). In group 2, 3 of the 4 patients with MM died within 15 months of diagnosis, but the 2 patients with LPL/WM are alive after 32 months. In group 1, only 1 patient died (of unknown causes) within 15 months after diagnosis. CONCLUSION: In patients with MCN, %UAE may be a useful marker for the detection of coexistence of glomerular lesions, such as amyloidosis, which are associated with a poor outcome.

Increase of 1,25 dihydroxyvitamin D in sarcoidosis patients with renal dysfunction.

INTRODUCTION: In sarcoidosis, renal involvement includes hypercalcemia-related nephrocalcinosis and granulomatous tubulointerstitial nephritis. Hypercalcemia is thought to be due to increased production of 1,25 dihydroxyvitamin D (1-25D), but 1-25D levels have not been evaluated in sarcoidosis patients with renal dysfunction. MATERIALS AND METHODS: We enrolled 9 sarcoidosis patients who underwent renal biopsy, and compared the serum 1-25D concentration and eGFR with those in 428 non-sarcoidosis patients who had renal dysfunction (stage 2 or higher CKD with an estimated glomerular filtration rate < 90). RESULTS: Serum calcium and 1-25D levels were significantly higher in the sarcoidosis patients than in the non-sarcoidosis patients (p < 0.01 and p = 0.01, respectively). There was a positive correlation between 1-25D and eGFR in the patients without sarcoidosis (r = 0.693; p < 0.01). As the renal function of sarcoidosis patients was improved by steroid therapy, the serum 1-25D and adjusted serum calcium levels decreased to near the median values in non-sarcoidosis patients. On renal biopsy, CD68 staining was positive for tissue macrophages in all 8 patients who had tubulointerstitial nephritis (with or without typical granulomas), while Von Kossa staining showed calcification of tubules near or inside granulomas in 6 of these 8 patients. CONCLUSION: While tissue macrophages promote development of tubulointerstitial nephritis and 1-25D overproduction in renal sarcoidosis, hypercalcemia secondary to elevation of 1-25D may be related to renal calcification and granuloma formation.

An Orofaciodigital Syndrome 1 Patient and Her Mother Carry the Same OFD1 Mutation but Have Different X Chromosome Inactivation Patterns.

Orofaciodigital syndrome 1 (OFD-1) is a rare, X-linked, dominantly inherited disorder caused by an OFD1 mutation that can cause polycystic kidneys. A 37-year-old woman on hemodialysis therapy was admitted to our hospital for trans-catheter arterial embolization therapy for enlarged polycystic kidneys. Lobulated tongue and brachydactyly were noticed, prompting an OFD1 sequencing analysis. Sequencing revealed a causal four-base-pair deletion in exon 13, both in the patient and in her mother, whose renal function had been retained. The peripheral leukocyte X chromosome inactivation pattern was skewed in the patient but not in her mother, suggesting some role in their phenotypic difference.

Long-term outcome of biopsy-proven cholesterol crystal embolism.

BACKGROUND: Cholesterol crystal embolism (CCE) causes renal damage, and there is an extremely high risk of end-stage renal disease. However, the time course of CCE-related renal deterioration varies and little is known about the subsequent risk of dialysis among patients with biopsy-proven CCE. METHODS: We performed a retrospective cohort study of 38 Japanese patients in whom a histological diagnosis of CCE was made from September 1992 to July 2005. Competing risk regression analysis was used to investigate the association between declining renal function ( ≥ 1.5 elevation of serum creatinine within 26 weeks after CCE) or its subtypes (acute [ < 1 week after CCE], subacute [1 to < 6 weeks], and chronic [6 to < 26 weeks]) and the risk of dialysis, with adjustment for age, baseline serum creatinine, and the precipitating event (iatrogenic or spontaneous). RESULTS: During a median follow-up period of 25.9 weeks, 14 patients (35.9%) started dialysis. Multivariable analysis showed that patients with declining renal function had a higher risk of commencing dialysis than those without declining function (subdistribution hazard ratio [SHR] 9.47; 95% confidence interval [CI] 1.34-66.8). Patients with different renal presentations had a similarly increased risk of commencing dialysis, with the risk being significantly higher for the subacute and chronic patterns of declining renal function (adjusted SHR [95% CI] for acute, subacute, and chronic declining renal function[vs. no decline]: 7.36 [0.85-63.6], 11.9 [1.36-101], and 10.7 [1.49-77.0], respectively). CONCLUSION: Declining renal function after CCE, even later than 6 weeks, was significantly associated with the subsequent risk of dialysis.

Renal-Limited Thrombotic Microangiopathy due to Bevacizumab Therapy for Metastatic Colorectal Cancer: A Case Report.

An 88-year-old Japanese man received bevacizumab for colorectal cancer with liver and peritoneal metastasis, during which nephrotic range proteinuria occurred (7.66 g/day). Renal biopsy showed endothelial damage with subendothelial swelling and a double contour of the glomerular basement membrane, which indicated a diagnosis of thrombotic microangiopathy (TMA). After bevacizumab was stopped, proteinuria decreased to 1 g/day. During the clinical course, this patient had no extrarenal manifestations. This case suggests that renal injury induced by bevacizumab is characterized by nephrotic range proteinuria and histological TMA, and is a renal-limited condition that differs from systemic TMA related to thrombotic thrombocytopenic purpura.

Arteriovenous fistula-related renal bleeding 5 days after percutaneous renal biopsy.

A 32-year-old Japanese woman was admitted to our hospital for evaluation of microscopic hematuria with a positive family history. Percutaneous renal biopsy was performed under real-time ultrasound guidance using a 16-gauge automated needle and three specimens were obtained. She had no risk factors for hemorrhage. However, macroscopic hematuria developed from 5 days after biopsy and persisted for 4 days. Her Hb decreased markedly from 15.0 to 8.1 g/dL. Enhanced computed tomography revealed urinary tract hematoma, while the early arterial phase showed inflow of contrast medium into the left renal vein from a pseudoaneurysm on a branch left renal artery. Renal transcatheter arterial embolization was performed using platinum microcoils and the arteriovenous fistula was occluded. The patient did not require blood transfusion. Severe renal bleeding that causes urinary tract hematoma usually occurs within 24 h after renal biopsy, but the possibility of late-onset renal bleeding should be kept in mind.

A familial case of pseudohypoaldosteronism type II (PHA2) with a novel mutation (D564N) in the acidic motif in WNK4.

BACKGROUND: There have been still few case reports of pseudohypoaldosteronism type II (PHA2), also known as Gordon's syndrome, genetically diagnosed, and this is the first report of familial PHA2 case in Japan with a novel D564N mutation in WNK4. METHODS: A 29-year-old woman was admitted to our hospital due to hyperkalemia (serum potassium: 6.4 mmol/L). She had mild hypertension (135/91 mm Hg), a bicarbonate level at the lower limit of the normal range (HCO3 : 22 mmol/L) with a normal anion gap, low plasma renin activity (0.2 ng ml-1  hr-1 ), and high urinary calcium excretion (505.4 mg/g Cre). A hereditary condition was suspected because her mother also had the same symptoms. We performed a comprehensive genetic analysis for major inherited kidney diseases with next-generation sequencing including the genes responsible for PHA2 (WNK1, WNK4, KLHL3, and CUL3). RESULTS: Genetic analysis revealed that the patient and her mother had a novel missense mutation (D564N) in the acidic motif in WNK4, which leads to the diagnosis of PHA2. Administration of trichlormethiazide (1 mg/day) effectively ameliorated her blood pressure (114/69 mm Hg), plasma bicarbonate (25 mmol/L), serum potassium (4.3 mmol/L), and urinary calcium excretion (27.2 mg/g Cre). CONCLUSION: We report the first Japanese familial case of PHA2 with WNK4 mutation. D564N mutation in WNK4 is a novel genetic cause of PHA2 with a relatively mild phenotype.