CEN Case Reports最新文献

{"title":"Severe growth retardation in Dent disease: a case report of a novel OCRL variant.","authors":"Okan Akacı, Erdal Eren","doi":"10.1007/s13730-026-01193-4","DOIUrl":"10.1007/s13730-026-01193-4","url":null,"abstract":"<p><strong>Introduction: </strong>Dent disease type 2 (DD-2) is a rare X-linked recessive renal tubulopathy caused by mutations in the OCRL gene. Clinically it is characterised by low molecular weight proteinuria (LMWP), hypercalciuria, and nephrocalcinosis. The phenotypic spectrum of DD-2 is expanding with the identification of new pathogenic variants.</p><p><strong>Case report: </strong>A 12-year-old male presenting with marked short stature and poor weight gain was found to have LMWP, haematuria, hypercalciuria, and bilateral nephrocalcinosis on initial clinical evaluation. Renal function was normal. There was no relevant family history. Genetic analysis revealed a hemizygous missense variant (c.899 C > A; p.Ala300Asp) in the OCRL gene, which has not been previously reported in the literature. No abnormalities were found on ocular or neurological examination as the same gene also causes Lowe syndrome. Therefore DD-2 was considered in this patient. Hydrochlorothiazide treatment was initiated but discontinued due to hypokalaemia. Growth hormone therapy was started by the endocrinology clinic due to severe growth retardation.</p><p><strong>Conclusion: </strong>Dent disease can present with a wide range of clinical findings. This case report describes a novel OCRL gene variant associated with DD-2. This newly identified variant contributes to the genotypic and phenotypic diversity of the disease, however, without functional validation, it is difficult to determine whether growth retardation is a significant complication in DD-2. Early diagnosis and a multidisciplinary approach are crucial for improving long-term outcomes.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13669284/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149179595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A case of immunofluorescence-negative light chain deposition disease diagnosed by mass spectrometry.","authors":"Mayu Iwata, Mineaki Kitamura, Tomohisa Tsuyuki, Naoki Akeho, Masamichi Ichinose, Hiroto Takaki, Emiko Otsuka, Kenta Torigoe, Ayuko Yamashita, Shinichi Abe, Hiroshi Yamashita, Hideki Tsushima, Kumiko Muta, Eisuke Katafuchi, Akira Shimizu, Hiroshi Mukae, Tomoya Nishino","doi":"10.1007/s13730-026-01186-3","DOIUrl":"10.1007/s13730-026-01186-3","url":null,"abstract":"<p><p>A 53-year-old man was referred to our department for the evaluation of kidney dysfunction and edema. Kidney biopsy revealed nodular glomerular lesions; however, immunofluorescence showed no specific deposition of immunoglobulins or light chains, and a definitive diagnosis could not be confirmed. Serum and urine immunofixation electrophoresis detected κ-type Bence Jones protein, raising suspicion of monoclonal immunoglobulin-related kidney disease. Bone marrow examination led to a diagnosis of multiple myeloma. Electron microscopy revealed band-like, powdery, electron-dense deposits extending from the glomerular basement membrane to the subendothelial area as well as deposits along the tubular basement membranes, suggestive of monoclonal immunoglobulin deposition disease. However, additional evaluation using immunofluorescence on paraffin-embedded tissues and immunohistochemical staining failed to demonstrate light-chain deposition, and a pathological relationship between the plasma cell disorder and kidney lesion could not be established. Laser microdissection followed by liquid chromatography-tandem mass spectrometry identified κ light chain deposition, leading to a definitive diagnosis of light chain deposition disease and providing pathological evidence linking the plasma cell disorder to the kidney lesion. Plasma cell-directed therapy was subsequently initiated, resulting in improved kidney function and the avoidance of dialysis. This case highlights the potential utility of mass spectrometry for establishing a definitive diagnosis and guiding therapeutic decision-making when light-chain deposition cannot be demonstrated by conventional or additional immunostaining.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13658694/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149164776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A case of renal hypouricemia type 1 associated with compound heterozygous URAT1/SLC22A12 variants A209V and F379L: clinical evidence for their pathogenic significance.","authors":"Naoyuki Otani, Marie Yamamoto, Tomoaki Takata, Shinobu Sugihara, Masanari Kuwabara, Masaharu Fukuki, Yusuke Endo, Seiko Shimizu, Akiyoshi Nakayama, Akihiro Otsuki, Hirotaka Matsuo, Kimiyoshi Ichida, Ichiro Hisatome","doi":"10.1007/s13730-026-01189-0","DOIUrl":"10.1007/s13730-026-01189-0","url":null,"abstract":"<p><p>Renal hypouricemia (RHUC) is an inherited renal tubular disorder characterized by low serum uric acid levels and excessive urinary uric acid excretion due to impaired urate reabsorption in proximal tubules. Type 1 RHUC (RHUC1) is caused by pathogenic variants in URAT1/SLC22A12. In Japanese patients, recurrent variants such as W258X and R90H account for a substantial proportion of RHUC1 cases; however, the clinical significance of rare URAT1 variant combinations remains incompletely understood. A 69-year-old woman was referred to our hospital for evaluation of renal dysfunction and hypouricemia. Laboratory examination revealed severe hypouricemia (serum uric acid, 0.7 mg/dL) and markedly increased urinary uric acid excretion (Cua/Ccr, 60.5%). She had chronic kidney disease (CKD) stage G3b and a renal stone. Genetic analysis identified two heterozygous variants, A209V and F379L, in URAT1/SLC22A12 gene. The variants were considered likely to represent compound heterozygosity based on the clinical phenotype and their previously reported functional impairment. Although A209V and F379L have individually been reported to impair urate transport, the clinical phenotype associated with this variant combination has not been well characterized. The severe hypouricemia and excessive urinary uric acid excretion observed in this patient provide clinical evidence supporting the pathogenic significance of the A209V and F379L combination. The coexistence of nephrolithiasis and CKD further raises the possibility that excessive urinary urate excretion and stone formation may contribute to renal dysfunction. In addition, the improvement in stone-related urinary abnormalities during potassium citrate treatment suggests that urinary alkalization may be beneficial in the management of nephrolithiasis associated with RHUC.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13658746/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149165336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Postoperative acute kidney injury associated with cast nephropathy and marked renal interstitial plasma cell infiltration in multiple myeloma: a case report.","authors":"Marika Sakai, Minato Umehara, Tetsuro Kusaba, Nariko Ikemura, Yu Mihara, Kazumi Komaki, Yuhei Kirita, Taku Tsukamoto, Naoko Takeda, Naoko Masuzawa, Keiichi Tamagaki","doi":"10.1007/s13730-026-01191-6","DOIUrl":"10.1007/s13730-026-01191-6","url":null,"abstract":"<p><p>Multiple myeloma (MM) is frequently associated with renal impairment, most commonly due to cast nephropathy. We report a case of severe and persistent postoperative acute kidney injury (AKI) in an 84-year-old man with smoldering MM who underwent posterior lumbar fixation for a lumbar burst fracture. Twelve hours after surgery, he developed profound hypotension and severe anemia due to surgical-site bleeding, followed by progressive renal dysfunction despite prompt transfusion and fluid resuscitation. Urinalysis revealed heavy proteinuria, and kidney biopsy demonstrated marked accumulation of eosinophilic casts within the tubules, consistent with cast nephropathy. In addition, marked renal interstitial infiltration by λ light-chain-restricted monoclonal plasma cells and focal peritubular capillary (PTC) occlusion were observed. Congo red staining was negative, and no significant glomerular immune deposits were detected. Renal function partially improved with supportive care but did not return to the preoperative baseline. This case suggests that postoperative AKI in MM may be multifactorial, with perioperative circulatory failure precipitating clinically overt cast nephropathy, while coexisting interstitial myeloma cell infiltration and focal PTC occlusion may increase susceptibility to ischemic injury and contribute to the severity and persistence of renal dysfunction. In patients with MM, latent myeloma-related kidney injury should be considered a potential contributor to perioperative AKI even when serum creatinine is preserved, particularly in those with marked proteinuria or elevated free light chain levels.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13658676/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149164887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Delayed eculizumab therapy guided by markedly elevated soluble C5b-9 in a child with dialysis-requiring acute poststreptococcal glomerulonephritis: a case report.","authors":"Ke Xu, Wei Bai, Suxia Wang, Yali Ren, Fang Wang","doi":"10.1007/s13730-026-01196-1","DOIUrl":"10.1007/s13730-026-01196-1","url":null,"abstract":"<p><p>Eculizumab, a monoclonal antibody targeting complement C5, has been shown to be effective when administered within 2-4 days of disease onset in children with severe acute poststreptococcal glomerulonephritis (APSGN). However, since APSGN typically follows a self-limited clinical course in most patients, the optimal timing and latest feasible time window for eculizumab initiation in APSGN remain undefined. A 9-year-old girl presented with gross haematuria, oliguria, and renal dysfunction 9 days after the onset of vomiting and abdominal pain. Laboratory tests showed a positive anti-streptolysin O titre, decreased serum complement C3 levels, massive proteinuria, and stage 3 acute kidney injury. Following high-dose methylprednisolone and continuous renal replacement therapy, her serum C3 levels recovered to normal range, yet oliguria and renal impairment persisted two weeks after disease onset. Since serum complement membrane attack complex (C5b-9) remained substantially elevated, eculizumab was initiated at a delayed time point compared with previous reports, yielding a rapid improvement in renal function. Kidney biopsy performed post-treatment with eculizumab revealed focal proliferative glomerulonephritis, accompanied by acute tubular injury. At the 6-month follow-up, except for haematuria detected by dipstick urinalysis, the patient had normal renal function, serum complement C3 levels and negative urinary protein. No severe adverse events occurred. We present a case of APSGN with persistent renal dysfunction and excessive complement activation 2 weeks after glucocorticoid therapy, who achieved substantial clinical remission upon eculizumab administration. Our observation suggests eculizumab may be an effective rescue intervention for persistent renal dysfunction in severe APSGN driven by excessive complement activation.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13658707/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149167984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early-onset autosomal dominant distal renal tubular acidosis caused by a de novo SLC4A1 R589C variant with growth failure and rickets.","authors":"Hajime Ito, Masumi Nagata, Koji Sakuraya, Reina Mayumi, Akina Matsuda, Keita Sakaguchi, Hiromichi Shoji","doi":"10.1007/s13730-026-01192-5","DOIUrl":"10.1007/s13730-026-01192-5","url":null,"abstract":"<p><p>Autosomal dominant (AD) distal renal tubular acidosis (dRTA) generally has a later onset and milder clinical course than autosomal recessive forms. However, delayed diagnosis may result in prolonged metabolic acidosis and severe growth impairment. Here we report the case of a Japanese boy with a de novo SLC4A1 (NM_000342.4):c.1765C > T (p.Arg589Cys) variant who presented with marked growth failure from 6 months of age and was diagnosed with AD-dRTA at 27 months. Because severe short stature was the predominant clinical feature, venous blood gas analysis was performed and revealed metabolic acidosis (pH 7.197, HCO₃^- 11.5 mmol/L). Additional investigations demonstrated hyperchloremia, hypokalemia, hypercalciuria, bilateral nephrocalcinosis, rickets, an inappropriately high urine pH, and a positive urinary anion gap. Targeted gene panel analysis using next-generation sequencing, followed by Sanger confirmation, established the genetic diagnosis. After initiation of alkali therapy, metabolic acidosis progressively improved; serum bicarbonate first reached the normal range at 9 months and remained within or close to the normal range thereafter. Radiographic improvement of rickets was observed within 3 months, before cholecalciferol supplementation was initiated, and substantial catch-up growth occurred during 5 years of follow-up, with the height standard deviation score improving from - 4.1 to - 2.3, while renal function remained preserved. Prolonged auxological and biochemical follow-up of early-onset SLC4A1-associated AD-dRTA has rarely been reported. This case illustrates that AD-dRTA may present during infancy and that assessment of acid-base status may facilitate timely diagnosis in children with otherwise unexplained growth failure.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13658732/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149164247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regression of uremic tumoral calcinosis following the switch from cinacalcet to etelcalcetide in a hemodialysis patient without severe hyperphosphatemia.","authors":"Takuya Hase, Shunsuke Goto, Hitomi Hara, Keisuke Oe, Tomoaki Fukui, Hideki Fujii","doi":"10.1007/s13730-026-01181-8","DOIUrl":"10.1007/s13730-026-01181-8","url":null,"abstract":"<p><p>Tumoral calcinosis (TC), a rare disease characterized by calcified mass formation in peri-articular soft tissue, manifests clinically as fractures, pain, and limited range of motion. In hemodialysis patients, severe hypercalcemia and hyperphosphatemia are major causes of the condition, and correcting these metabolic disorders reportedly induces its regression. Herein, we report the case of a 46-year-old man on maintenance hemodialysis who developed TC that regressed following etelcalcetide therapy despite the absence of severe hyperphosphatemia. The patient had started hemodialysis at age 32, and soft tissue calcifications were first noted two years later. These progressed to TC, which caused a left femoral shaft fracture 13 years after the initiation of dialysis. When the fracture occurred, TC was present in both thighs and the left elbow. Seven months after the fracture, he was referred to our department. Laboratory findings showed serum phosphate, corrected calcium, and intact parathyroid hormone levels of 4.9 mg/dL, 10.3 mg/dL, and 109 pg/mL, respectively. Cinacalcet was switched to intravenous etelcalcetide hydrochloride, and significant regression of the remaining TC was observed six months after the switch. Our findings suggest that etelcalcetide may be effective for TC in patients on hemodialysis, even in the absence of severe hypercalcemia or hyperphosphatemia. However, further reports are required to determine whether this observation is generalizable.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653017/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149147562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pediatric anti-GBM crescentic glomerulonephritis: partial renal recovery following plasmapheresis and mycophenolate mofetil.","authors":"Quynh Trang Nguyen, Thu Huong Nguyen, Thien Nam Thai, Ngoc Thach Hoang, Thi Ngoc Nguyen","doi":"10.1007/s13730-026-01184-5","DOIUrl":"10.1007/s13730-026-01184-5","url":null,"abstract":"<p><p>Anti-glomerular basement membrane (anti-GBM) glomerulonephritis is a rare cause of rapidly progressive glomerulonephritis in children. The disease is characterized by the formation of antibodies against the glomerular basement membrane, leading to diffuse glomerular injury and rapid deterioration of renal function if not diagnosed and treated promptly. We report the case of a 14 year-old girl who was admitted with acute-onset edema and hypertension. Initial investigations revealed hematuria, proteinuria, hypoalbuminemia, progressive renal impairment, and positive anti-GBM antibodies. Kidney biopsy confirmed the diagnosis, demonstrating diffuse crescentic glomerulonephritis with linear IgG deposition along the glomerular basement membrane. The patient was treated with high-dose corticosteroids, plasmapheresis, and mycophenolate mofetil. After three months of treatment, both clinical and laboratory parameters improved, with partial recovery of renal function. This case highlights the importance of early recognition and prompt treatment of pediatric anti-GBM disease and suggests that an MMF-containing combination regimen may be a feasible alternative to cyclophosphamide-based therapy in selected patients.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 6","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13650238/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149135249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FAT1-associated membranous nephropathy after hematopoietic stem cell transplantation: a case report and review of the literature.","authors":"Ryosuke Saiki, Kan Katayama, Yuto Matsui, Tomohiro Murata, Kaoru Dohi","doi":"10.1007/s13730-026-01188-1","DOIUrl":"https://doi.org/10.1007/s13730-026-01188-1","url":null,"abstract":"<p><p>We report a 55-year-old man who developed nephrotic syndrome 52 months after allogeneic hematopoietic stem cell transplantation for acute lymphoblastic leukemia. He had chronic graft-versus-host disease controlled with low-dose prednisolone and tacrolimus. Asymptomatic proteinuria was detected five months before referral, followed by progressive edema, massive pleural effusion, and ascites. At presentation, laboratory testing showed profound hypoalbuminemia, mildly reduced kidney function, and nephrotic-range proteinuria. Kidney biopsy demonstrated membranous nephropathy, with periodic acid-methenamine silver staining showing spikes and bubbling of the glomerular basement membrane. Immunofluorescence showed granular capillary-wall immunoglobulin G staining with immunoglobulin G1 predominance over immunoglobulin G4, and protocadherin FAT1 immunofluorescence showed granular staining along the glomerular basement membrane. Prednisolone was increased from 5 to 30 milligrams per day while tacrolimus was continued, resulting in improved proteinuria, serum albumin, edema, and kidney function at five months without clinically significant infectious complications. We also reviewed 29 reported cases of protocadherin FAT1-associated membranous nephropathy after hematopoietic stem cell transplantation, including the present case. The review showed variable onset timing, substantial proteinuria at presentation, inconsistent immunoglobulin G4 positivity, and heterogeneous treatment with corticosteroids, rituximab, calcineurin inhibitors, and other regimens. Our case and review indicate that this disease can present late, cannot be excluded by non-immunoglobulin G4-predominant staining, and remains heterogeneous in diagnostic evaluation, treatment, and outcomes. Further accumulation of cases is needed to clarify the clinical spectrum and optimal management of this disease.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 5","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13627484/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149104681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"When two rare diseases meet: atypical hemolytic uremic syndrome and alkaptonuria in two siblings.","authors":"Cebrail Karaca, Beril Karatas, Ruhat Tunc, Mehmet Erdem, Mevlut Tamer Dincer, Safak Mirioglu","doi":"10.1007/s13730-026-01187-2","DOIUrl":"https://doi.org/10.1007/s13730-026-01187-2","url":null,"abstract":"<p><p>Atypical hemolytic uremic syndrome (aHUS) is a rare complement-mediated thrombotic microangiopathy (TMA), whereas alkaptonuria (AKU) is an uncommon inherited metabolic disorder. Their coexistence has not previously been described. We report two siblings from a consanguineous family with CD46-associated aHUS and AKU to highlight an unusual diagnostic challenge and the importance of recognizing coexisting inherited diseases. Two brothers experienced recurrent episodes of TMA characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, while maintaining preserved long-term renal function despite persistent proteinuria. Genetic analysis identified a homozygous CD46 variant consistent with familial aHUS. During evaluation, recurrent black discoloration of urine, chronic back and knee pain, scleral pigmentation, and a history of black-stained diapers since infancy suggested an additional inherited disorder. Subsequent testing confirmed a homozygous pathogenic HGD variant, establishing the diagnosis of AKU. Both patients achieved hematologic remission following complement inhibition and remained free of dialysis throughout follow-up. To our knowledge, this is the first report of the coexistence of aHUS and AKU. These cases demonstrate that persistent or recurrent black discoloration of urine in patients with TMA should not be assumed to result solely from hemolysis. Careful assessment of atypical clinical features, supported by genetic testing when appropriate, may facilitate recognition of coexisting inherited disorders, particularly in consanguineous families, and improve diagnostic accuracy and long-term patient management.</p>","PeriodicalId":9697,"journal":{"name":"CEN Case Reports","volume":"15 5","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13627559/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149104694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}