Mitsuru Okada

A boy with Japanese Dent's disease exhibiting abnormal calcium metabolism and osseous disorder of the spine: defective megalin expression at the brushborder of renal proximal tubules.

We encountered a 16-year-old boy with Japanese Dents disease who exhibited renal insufficiency and an osseous disorder of the spine. Proteinuria first was noted at the age of 2 years. At 13 years, the patient underwent analysis of the CLCN5 gene, which identified missense mutation (I524K) in exon 10. During follow-up, a marked increase in urinary beta2-microglobulin was associated with mild deterioration of renal function. At the age of 15 years, hypocalcemia (7.5 mg/dl) accompanied by an increased plasma concentration of alkaline phosphatase was first detected. At that time, plasma concentration of 25(OH)D3 and 1alpha25(OH)2D3 were low accompanied by a high plasma parathyroid hormone concentration. A renal biopsy specimen revealed tubulointerstitial alterations including mononuclear cell infiltration, partial fibrosis and focal glomerular sclerosis. Immunofluorescence revealed weak, discontinuous staining of megalin along the brushborder of renal proximal tubules. Western blotting demonstrated decreased urinary excretion of megalin. Thus, clinical manifestations and prognosis may vary in Japanese Dents disease. Reduced megalin expression may have disturbed calcium homeostasis, leading to osseous disorder in our patient.

A Japanese family with Alport syndrome associated with esophageal leiomyomatosis: genetic analysis of COL4A5 to COL4A6 and immunostaining for type IV collagen subtypes.

BACKGROUNDnIn some families, X-linked Alport syndrome (AS) is associated with diffuse leiomyomatosis. We describe clinical, pathologic and molecular-genetic findings in a Japanese family with this inheritance mode of AS in association with leiomyomatosis.nnnPATIENTnAS was diagnosed in a one-year-old boy with recurrent aspiration pneumonia caused by esophageal stenosis from leiomyomatosis. Diagnosis was confirmed by electron microscopy coupled with type IV collagen chain subtype staining in a renal biopsy specimen. His mother, who exhibited esophageal leiomyomatosis and is heterozygous for AS, showed a discontinuous staining pattern for collagen alpha5(IV) chain along the epidermal basement membrane in a skin biopsy specimen. Genetic analysis in the boy revealed the deletion of the first two exons of COL4A6 together with deletion of the 5 end of COL4A5. Despite administration of cyclosporin A, massive proteinuria has persisted in the boy, although renal function otherwise remains normal.nnnCONCLUSIONnIdentification of an AS patient during infancy is extremely rare. Clinical manifestations, including macroscopic hematuria, cataracts and leiomyomatosis caused by the large deletion involving COL4A5 to COL4A6, led to early presentation with AS.

Chronic renal insufficiency in a boy with cystic renal lymphangiectasia : morphological findings and long-term follow-up

Cystic renal lymphangiectasia (CRL) is a rare malformation of lymphatics that can present in childhood and adulthood. Symptoms and radiologic features are relatively well defined, but clinical evolution and prognosis remain unclear. We treated a boy with CRL who developed chronic renal insufficiency. The first manifestation was abdominal swelling associated with an umbilical hernia noted incidentally at 1.6 years. Computed tomography with intravenous contrast administration demonstrated perirenal cysts with fluid collection, suggesting CRL. Intractable ascites resisted pharmacologic treatments such as diuretics. After approximately 7 years, the ascites resolved spontaneously, but the perirenal cysts persisted. At 11 years, proteinuria was noted. A renal biopsy specimen showed interstitial abnormalities consistent with CRL, glomeruli showed a focal segmental mesangial increase. Proteinuria persisted despite administration of an angiotensin-converting enzyme inhibitor, increasing as obesity and hypertension worsened. Renal function gradually declined in the ensuing years. Polycythemia coexisted with a normal serum erythropoietin concentration. A follow-up renal biopsy specimen disclosed glomerular enlargement together with focal segmental mesangial expansion, suggesting obesity-related glomerulopathy. Our observation suggest that under some specific circumstances like our patient CRL may exacerbate. Management of complicating obesity and hypertension are likely to be important for maintaining normal renal function, especially in the diffuse bilateral type of CRL present in our patient.

Alport syndrome and benign familial hematuria (thin basement membrane disease) in two brothers of a family with hematuria

Alport syndrome (AS) and benign familial hematuria (BFH) are inherited disorders of the glomerular basement membrane, which are sometimes difficult to differentiate at the early stage without type IV collagen staining of the renal basement membrane. Previous studies have indicated that mutation of type IV collagen alpha4 gene may be responsible for both BFH and AS. We report here a Japanese family with consanguinity, in which autosomal-recessive AS and BFH were separately identified in two brothers on the basis of findings of electron microscopy and type IV collagen chain staining of the renal biopsy specimens. Their parents, being first cousins, paternal uncle and grandmothers were found to have hematuria. Our observations suggest that BFH patients were heterozygous carriers of autosomal-recessive AS.

A case of renal-coloboma syndrome associated with mental developmental delay exhibiting a novel PAX2 gene mutation.

A case of an adolescent male with renal-coloboma syndrome (RCS) showing developmental delay is described. Birth and perinatal histories were typical. Proteinuria was initially observed at the age of 7 years during an annual mass screening program for school children. His urine was checked periodically at a local hospital. Because of an increase in proteinuria, he was referred to our hospital for further clinical evaluation. Proteinuria was moderate, ranging from 1.0 to 1.5 g/day, and was coupled with mild renal dysfunction. At that time, he was found to have myopia associated with astigmatism. He exhibited mild developmental delay, assessed by a WISC-III test. A renal biopsy sample showed marked glomerular enlargement, collapse of glomerular capillaries, mesangial matrix expansion, and tubulointerstitial change, demonstrating typical histologic features of RCS. Approximately five years after starting follow-up, the patient had severe renal dysfunction. Furthermore, optic nerve coloboma was also evident. Genetic analysis of the patient revealed a novel heterozygous mutation in exon 3 of the PAX2 gene (P130H).

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.

An adolescent with marked hyperimmuno-globulinemia E showing minimal change nephrotic syndrome and a STAT3 gene mutation

We encountered a patient with marked hyperimmunoglobulinemia E who had a mutation of the signal transducer and activator of transcription 3 gene (STAT3) and developed minimal change nephrotic syndrome (MCNS). From early infancy, the patient showed repeated episodes of refractory chronic eczema accompanied by impetigo vulgaris with cicatrization, as well as otitis media. Serum IgE was markedly increased (from 4,000 to 25,000 IU/ml). The nephrotic syndrome (NS) frequently relapsed, and was alternately responsive and resistant to corticosteroids. The STAT3 mutation was heterozygous, located in exon 23 of the transactivation domain and causing A744V substitution. Presently treated with mycophenolate mofetil, the patient has less frequent MCNS recurrences. Increases in circulating Th2 cytokines and IgE combined with suppression of the Th1 cytokine interferon-γ caused by the STAT3 abnormality, presumably caused MCNS by altering the Th1/Th2 balance among T-lymphocytes. To our knowledge, this is the first report of type I hyper-IgE syndrome (HIES) showing a STAT3 gene mutation and MCNS.

A female infant with Frasier syndrome showing splice site mutation in Wilms' tumor gene (WT1) intron 9.

Wilms tumor gene (WT1) abnormality leads to various disorders of differentiation as well as renal and urinary system abnormalities. Here we present a case of WT1 abnormality and steroid-resistant nephrotic syndrome in a female infant. The 3-year-old patient was initially diagnosed with proteinuria at an annual mass screening program for children aged three years and was referred to our hospital. She met the diagnostic criteria for nephrotic syndrome and showed normal renal function. The patient was treated with corticosteroids; however her condition showed resistance to corticosteroids. On renal biopsy, she was diagnosed with focal segmental glomerulosclerosis (FSGS). Because of the possibility of WT1 abnormality, an exon array analysis was conducted, which ruled out Denys-Drash Syndrome (DDS). The patient was then diagnosed with Frasier Syndrome (FS) on the basis of donor site mutation (IVS9+5G > A) of the splice site in the intron 9. Reports of female infants with FS are extremely rare. FS is one of the pre-mRNA splicing diseases, in which the occurrence of symptoms is associated with a decrease in the ratio of the lysine-threonine-serine (+/- KTS) isoform of the WT1 protein. A typical case exhibits 46 XY male karyotype and is characterized by male pseudohermaphroditism with cord-like gonadal structures as well as progressive nephropathy caused by FSGS. However, in female infants without such extrarenal signs, it is necessary to consider the analysis for WT1 intron 9 for conclusive diagnosis of FS, because the presence of nephropathy is the only symptom for possible detection.

Association of INVS (NPHP2) mutation in an adolescent exhibiting nephronophthisis (NPH) and complete situs inversus.

Cystic kidney disease has been linked to mutations in the Invs gene in mice with an inversion of embryonic turning (inv/inv) and the INVS (NPHP2) gene in human infantile nephronophthisis (NPH). Infantile NPH shows marked cyst formation in contrast to other forms of NPH and rapidly progresses to end-stage renal failure (ESRD) before 5 years of age. In this report, we describe an adolescent with a mutation in INVS who had preservation of his renal function beyond infancy. The patient showed findings of NPH with mild renal insufficiency together with situs inversus. He also exhibited a series of features consistent with Jeune syndrome involving asphyxiating thoracic dystrophy, heart failure and hypertension prior to advanced renal insufficiency. Based upon these features, our patient is likely to have the combined clinical features of infantile NPH with Jeune syndrome. Genetic analysis for INVS disclosed a heterozygous mutation of TrG at position rs7024375 in the 5UTR of INVS in the patient and his mother, while no abnormalities were found in any of the 17 exons of INVS or NPHP1, 3 and 4. To our knowledge, this is the first patient possessing a genetic alteration in INVS who had preservation of renal function past childhood. This study suggests that our patient may be a compound heterozygote for infantile NPH and Jeune syndrome, because both these disorders are transmitted mainly as an autosomal-recessive trait.

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

INTRODUCTIONnWe 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.nnnMETHODSnTo 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).nnnRESULTSnIn 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.nnnCONCLUSIONnOur 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.