Tomoki Miyazawa

A tubulointerstitial nephritis antigen gene defect causes childhood-onset chronic renal failure.

Tubulointerstitial nephritis antigen (TIN-ag), which has been localized to the renal tubular basement membrane, is a target antigen in some forms of TIN. Physiologically, TIN-ag is thought to be important in maintaining the structure of renal tubular basement membrane. Here we describe a child with chronic renal failure showing a human TIN-ag gene (hTIN-ag) deletion. Immunohistochemical examination using an antihuman TIN-ag monoclonal antibody showed attenuation or lack of TIN-ag staining along the renal tubular basement membrane, whereas nephrocystin staining was normal in renal tubules. Polymerase chain reaction detected no amplification band corresponding to hTIN-ag in this patient. Testing for a deletion in this gene showed nearly complete deletion. By using array-comparative genomic hybridization method, large deletion of a gene mapped on chromosome 6p11-6p12 was demonstrated, corresponding to the locus where hTIN-ag is located. Therefore, an hTIN-ag defect may be a potent cause of end-stage renal failure in childhood.

Newly-identified symptoms of left renal vein entrapment syndrome mimicking orthostatic disturbance

BackgroundIn addition to the urinary abnormalities, symptoms of left renal vein entrapment between the aorta and superior mesenteric artery (left renal vein entrapment syndrome, LRVES) may include abdominal and flank pain as well as chronic fatigue. We investigated various LRVES symptoms in this study.MethodsIn 53 pediatric LRVES patients treated at our department, 22 had a score of 5 points or higher on orthostasis. Initial evaluation of LRVES by abdominal ultrasonography showed a stenotic-to-prestenotic vein diameter ratio of 0.2 or less. Definitive diagnosis was made by computed tomography and magnetic resonance angiography. Cortisol, catecholamine (CA), and brain natriuretic peptide (BNP) were also measured.ResultsThe frequency of LRVES was 2.5 times higher in girls than in boys. Low or very low body mass indexes were seen in both sexes. The most common initial finding was urine abnormalities, followed by dizziness and malaise. In 6 patients, orthostasis precluded school attendance. Ten patients had orthostasis scores above 12. Patients unable to attend school had either low levels of plasma or urinary cortisol. Midodrine significantly decreased orthostasis scores. Some patients required treatment with fludrocortisone. Plasma CA, renin, and BNP levels were all normal.ConclusionsLocally excessive venous pressure may cause reversible adrenal dysfunction with transitory Addisonian symptoms. Children with cryptogenic malaise or severe orthostasis should be evaluated for LRVES.

Low-density lipoprotein adsorption therapy can restore drug sensitivity for immunosuppressants via inhibitory effects upon MDR-1 gene expression.

In two patients with steroid‐resistant nephrotic syndrome (SRNS), we investigated the relationship between clinical findings during immunosuppressive therapy and multiple drug resistant gene‐1 (MDR‐1) expression. MDR‐1 was detected by real‐time polymerase chain reaction (PCR). In a boy who initially developed SRNS at 3 years, we observed MDR‐1 expression over 3 years. Maximal and minimal MDR‐1 expression were 90 000 and 7800 copies/µg RNA, respectively. In a 4‐year‐old boy who initially developed SRNS at 3 years, we determined MDR‐1 expression over 2 years. Maximal and minimal MDR‐1 expression were 42 000 and 6900, respectively. MDR‐1 evaluation requires determination of MDR‐1 expression at several time points in a clinical course. Establishment of a normal expression may be needed for each individual patient. Increasing MDR‐1 during remission was followed soon by recurrences, an observation that may be a guide for therapeutic choice. LDL influences a humoral factor involved in MDR‐1 expression. Both patients responded to LDL adsorption therapy because of elevated LDL levels. While cyclosporine A therapy gradually decreased MDR‐1 expression, LDL adsorption therapy decreased expression sharply. Based on the results of the present study, LDL adsorption therapy could contribute to the amelioration of drug sensitivity for immunosuppressants including corticosteroids via inhibitory effects on MDR‐1 expression.

Childhood Cogan syndrome with aortitis and anti-neutrophil cytoplasmic antibody-associated glomerulonephritis.

Cogan syndrome is a systemic disease manifesting interstitial keratitis, sensorineural hearing loss, tinnitus, and rotatory vertigo. Renal complications of this syndrome are very rare. We encountered an adolescent with Cogan syndrome complicated by aortitis and anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis. At the age of 14, the patient showed proteinuria in a screening urinalysis at school and was found to lack a right radial pulse. Magnetic resonance angiography disclosed right subclavian artery stenosis. Examination of a renal biopsy specimen showed ANCA-positive crescentic glomerulonephritis. Steroid and immunosuppressant treatment improved renal function and histopathology, but repeated recurrences followed. At 18, the patient developed rotatory vertigo, a sense of ear fullness, and sensorineural hearing loss. The patient was diagnosed with Cogan syndrome. We know of no previous description of ANCA-positive crescentic glomerulonephritis in children with Cogan syndrome. Accordingly, evaluation of aortitis in childhood should include not only otolaryngologic and ophthalmologic examinations, but also periodic urine examination and renal function tests.

Pediatric Left Renal Vein Entrapment Syndrome Diagnosed by 99mTc-Albumin-Conjugate Scintigraphy

Background/Aims: Procedures for diagnosis of left renal vein entrapment syndrome (LRVES) in children have been either invasive or limited in accuracy. We examined scintigraphy with 99mTc-diethylene triamine pentaacetic acid-conjugated human serum albumin (99mTc-HSA-D) scintigraphy in childhood LRVES, demonstrating selective left renal nuclides excretion. We also measured peak velocity using pulse Doppler ultrasonography, calculating pressure differences between inferior vena cava and left renal vein using a simplified Bernoulli equation. Methods: Thirteen patients provisionally diagnosed with LRVES by ultrasonography combined with other imaging such as magnetic resonance angiography and three-dimensional computer tomography (CT) were examined. Results: Four children showing repeated gross hematuria all showed pressure differences exceeding 3.0 mm Hg. Selective left renal albumin excretion was demonstrated by 99mTc-HSA-D scintigraphy. Single-photon emission CT also showed accumulation in a site consistent with the left renal pelvis. Among 9 children manifesting mainly orthostatic proteinuria, selective left renal albumin excretion examined by 99mTc-HSA-D scintigraphy was demonstrated only in those with proteinuria exceeding 1 g/g Cr after standing in a lordotic position. Pressure differences in patients with orthostatic proteinuria were unrelated to proteinuria severity. Conclusions: Combining pulse Doppler ultrasonography with 99mTc-HSA-D scintigraphy, both noninvasive and safe in children, may suffice for diagnosis of LRVES, especially with gross hematuria.

Effect and therapeutic mechanisms of tonsillectomy for childhood IgA nephropathy

Aim:  We investigated efficacy and therapeutic mechanisms of tonsillectomy for intractable childhood IgA nephropathy. Five patients refused tonsillectomy. Among 25 patients, 19 patients were able to evaluate histological findings before and after surgery. Patients with poor (n = 7) or relatively poor (n = 18) histologically determined prognosis and an age of at least 7 years, together with proteinuria of at least 0.3 g/day or severe persisting despite ongoing drug treatment, are candidates for surgery. Patients were grouped by interval between diagnosis of IgA nephropathy and tonsillectomy (within 3 years; early group vs 3 years or later; later group). Patients underwent kidney biopsy shortly before and 1 to 2 years after tonsillectomy.

Renal tubular dysgenesis and tubulointerstitial nephritis antigen in juvenile nephronophthisis

Aim:  The relationship between abnormalities of tubular architecture and tubulointerstitial nephritis antigen (TIN‐ag) in juvenile nephronophthisis (J‐NPH) was evaluated.

Cyclosporine A causes maturation failure in embryonic-type glomeruli persisting after birth.

INTRODUCTION We analyzed renal histologic and immunohistologic findings in children with nephrotic syndrome (NS) who did (n=5) or did not (n=17) develop cyclosporine A (CyA) nephropathy despite appropriately low serum CyA concentrations being maintained over 2 years. METHODS To discriminate embryonic-type from mature glomeruli, we performed staining for type IV collagen a1, laminin ß1 and laminin ß2. Staining patterns were used to semiquantitatively assess glomerular immaturity (glomerular immaturity index, or GII). RESULTS In follow-up biopsy specimens, residual embryonic-type, collapsed embryonic-type and sclerotic glomeruli that had failed to differentiate were observed. Patients with early-onset CyA nephropathy had a high GII. In patients with a high GII, arteriopathy developed early in CyA treatment. Arteriopathy was observed mostly near embryonic-type glomeruli. Taken together, these glomeruli (surviving embryonic-type, collapsing embryonic-type, and sclerotic glomeruli) essentially equaled the total number of embryonic-type glomeruli in specimens obtained before CyA treatment. CONCLUSION Our findings indicate a need for caution in CyA therapy for patients with NS, even for a relatively short course of administration, because some patients may have embryonic-type glomeruli or immature arterioles that predispose them to CyA nephropathy.

A patient with Henoch-Schönlein purpura manifesting unusual symptoms and clinical course.

We evaluated and treated a girl with Henoch-Schönlein purpura (HSP), who initially developed redness, swelling, and pain in all 4 limbs accompanied by Raynaud syndrome and then had convulsions and disturbance of consciousness. HSP was diagnosed based on later findings of purpura in both legs and a decrease in factor XIII activity not accompanied by thrombocytopenia. She was normotensive. A skin biopsy specimen showed small-vessel vasculitis accompanied by immunoglobulin A deposition. The cause of erythema and limb pain, convulsions, and disturbed consciousness presumably was vasculitis. The possibility of HSP should be considered in patients with limb pain despite initial absence of purpura and in patients with central nervous system symptoms such as convulsions.

Three patients with Schaaf-Yang syndrome exhibiting arthrogryposis and endocrinological abnormalities

MAGEL2 is the paternally expressed gene within Prader–Willi syndrome critical region at 15q11.2. We encountered three individuals in whom truncating mutations of MAGEL2 were identified. Patients 1 and 2, siblings born to healthy, non‐consanguineous Japanese parents, showed generalized hypotonia, lethargy, severe respiratory difficulty, poor feeding, and multiple anomalies including arthrogryposis soon after birth. We carried out whole‐exome sequencing, which detected a MAGEL2 mutation (c.1912C>T, p.Gln638*, heterozygous). The patients’ father was heterozygous for the mutation. Patient 3 was a female infant, showed respiratory difficulty reflecting pulmonary hypoplasia, generalized hypotonia, feeding difficulty and multiple anomalies soon after birth. Targeted next‐generation sequencing detected a novel heterozygous mutation in MAGEL2 (c.3131C>A, p.Ser1044*). This mutation was not found in the parents. MAGEL2 mutations, first reported to be the cause of the Prader–Willi like syndrome with autism by Schaaf et al. (2013) Nature Genetics, 45: 1405–1408 show the wide range of phenotypic spectrum from lethal arthrogryposis multiplex congenital to autism spectrum disorder (ASD) and mild intellectual disability (ID). Our results indicate that MAGEL2 mutations cause multiple congenital anomalies and intellectual disability accompanied by arthrogryposis multiplex congenita and various endocrinologic abnormalities, supporting that the view that clinical phenotypes of MAGEL2 mutations are variable.