Hypocomplementemic type II membranoproliferative glomerulonephritis in a male patient with familial lecithin-cholesterol acyltransferase deficiency due to two different allelic mutations.

Patients with familial lecithin-cholesterol acyltransferase (LCAT) deficiency very often show progressive glomerulosclerosis with evolution to end-stage disease. High levels of an abnormal lipoprotein (lipoprotein X) cause glomerular capillary endothelial damage. The ultrastructural study of renal biopsy specimens shows characteristic glomerular deposits of membrane-like, cross-striated structures and vacuole structures. The gene encoding for LCAT has been mapped to chromosome 16q22.1, and several mutations of this gene cause LCAT deficiency which is inherited as an autosomal recessive trait and which is characterized by corneal opacities, normochromic normocytic anemia, and renal dysfunction. Herein we report clinical features and renal histological findings concerning a 24-year-old male patient with classical familial LCAT deficiency due to two different allelic mutations: a nonsense mutation inherited from the father and a missense mutation inherited from the mother. Moreover, the patient showed glomerular histological lesions and an immunofluorescent glomerular pattern typical of hypocomplementemic membranoproliferative type II glomerulonephritis (dense-deposit disease). The nature of electron-dense material that characterizes dense-deposit disease is still unknown, but there are suggestions that some chemical modifications might occur in the renal basement membranes. Therefore, this clinical case might induce to consider possible relations between disorders of the lipoprotein metabolism and renal dense-deposit disease.

Ultrastructural and immunohistochemical findings in Alport's syndrome: a study of 108 patients from 97 Italian families with particular emphasis on COL4A5 gene mutation correlations.

A total of 108 patients affected by Alport's syndrome, taken from 97 families, were enrolled in a genetic and ultrastructural study. Sixty-four families (75 patients) were X-linked, seven autosomal recessive, two autosomal dominant, five uninterpretable, and 19 sporadic. The ultrastructural features were consistent with Alport's syndrome in 66, doubtful in 20, and not significant for Alport's syndrome in 22 patients in the X-linked, sporadic, and genetically uninterpretable groups (without significant differences), as well as in the autosomal group. Mutations of the COL4A5 gene were present in 36 patients in the first three groups, without significant differences. More severe mutations were more frequently present in patients with an ultrastructural pattern consistent with Alport's syndrome. Nevertheless, there seems to be no strict correlation between mutation and ultrastructure, because a major rearrangement was found in a patient with no significant lesions, and different morphologic patterns were detected in patients Belonging to the same family. Immunohistochemical investigation into 24 patients for alpha (IV) chains showed that both alpha 3(IV) and alpha 5(IV) were lacking in the glomerular basement membrane of 13 patients (five with mutations) and were expressed in another six (three with mutations and one in the autosomal group). On the contrary, in this study the retained expression of alpha 3(IV) chain was found, despite the lack of alpha 5(IV) in the glomerular basement membrane of five patients (two with mutation). These different patterns could be related to both the type and severity of the COL4A5 mutations. All of the ultrastructural patterns were identified in all three immunohistochemical groups. Ultrastructural features and alpha 5(IV) chain production, even if an expression of a genetic mutation, do not strictly correlate. The combined use of analysis of collagen expression and electron microscopy made it possible to diagnose Alport's syndrome in 92% of the cohort, and therefore this approach is advisable. A multidisciplinary approach is recommended in the study of Alport's syndrome in an attempt to achieve a better diagnostic definition of and insight into the pathogenetic mechanisms.

Eliminant effects of calcitonin gene related peptide on the tubular epithelial cells in an isolated and perfused rat kidney.

The effect of the infusion of calcitonin gene related peptide (CGRP) on the renal structure and enzyme release from tubular epithelial cells was studied. This study was performed in the model of an isolated perfused kidney to avoid the systemic effects and complex hormonal and neuromediated interaction following the CGRP infusion in the intact experimental animal. After infusion of CGRP, the perfused kidney, studied by semiquantitative histology and electron microscopy, did not show any alteration at the glomerular level; however, important histological lesions were apparent at the proximal tubular level: the brush border was destroyed and the epithelial cells were markedly flattened. This structural damage to epithelial cells was confirmed by electron microscopy. The alanine amino peptidase (AAP) and N-acetyl-glucosaminidase (NAG) were significantly increased in the effluent of the perfusion system, in confirmation of the histological damage. The direct toxic effect of CGRP on the tubular epithelial cells may be related to the reabsorption and tubular transport of this substance.

Renal transplantation from living donor parents in two brothers with Alport syndrome. Can asymptomatic female carriers of the Alport gene be accepted as kidney donors?

Renal transplantation from living donor parents was performed in two brothers with end-stage renal failure due to Alport syndrome (AS). Two years later, the patient receiving the kidney graft from the mother, obligate carrier of AS, presented persistent microhematuria and proteinuria with normal renal function. The histological study demonstrated ultrastructural glomerular lesions consistent with AS. The authors conclude that: (1) Alport patients should not be deprived of renal transplantation from living donors, since anti-GBM nephritis is a rare complication; (2) an oligosymptomatic female carrier of the Alport gene may be considered as living renal donor, although a longer follow-up is needed in order to draw definitive conclusions.

Variability of clinical phenotype in a large Alport family with Gly 1143 Ser change of collagen alpha 5(IV)-chain.

In a large Italian family with adult-onset Alport syndrome, molecular analysis of the COL4A5 gene, which encodes the alpha 5(IV)-chain of glomerular basement membrane collagen, revealed a GGC-->AGC change in exon 38, resulting in substitution of a serine for a glycine in position 1143 of the polypeptide chain, between interruptions 19 and 20 of the triple helical domain. The mutation leads to loss of a restriction site for the enzyme Msp I, and could thus be easily recognized in several female and male relatives. Among relatives of both sexes who carried the same mutation, the clinical phenotype of Alport syndrome was variable as for the onset of renal failure and the presence of associated ear and eye abnormalities.

IgA mesangial nephropathy associated with renal cell carcinoma.

The authors report the occurrence of proliferative glomerulonephritis with mesangial IgA deposits in a 47-year-old man, heavy smoker, affected with renal cell carcinoma at stage I. The relationship between neoplastic diseases and IgA glomerulonephritis is unresolved. It is possible that IgA mesangial nephropathy may occur as a paraneoplastic disease, but in this patient its association with renal cell carcinoma may be merely fortuitous.

IgA glomerulonephritis in Wiskott-Aldrich syndrome.

Renal morphology was evaluated in 2 siblings with Wiskott-Aldrich syndrome (WAS) aged 12 and 4 years. They gave a typical history of recurrent episodes of respiratory infection and presented with microhematuria of glomerular origin and proteinuria. The study disclosed a membranoproliferative glomerulonephritis with IgA mesangial deposition in the elder child, while immunofluorescence was negative in the younger. The data indicate that (1) a specific nephropathy does not exist in WAS and (2) the IgA nephropathy is the result of recurrent infections and of related formation of IgA immune complexes scarcely removed by a deficient reticuloendothelial system. This view is consistent with presenting features in WAS (microhematuria, episodes of macrohematuria, proteinuria, Henoch-Schönlein syndrome) and with the fact that it takes years to develop as indicated by the negativity of immunofluorescence in the younger patient.