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Background. Alport syndrome (ATS) is a progressive inherited nephropathy characterized by irregular thinning, thickening and splitting of the glomerular basement membrane (GBM) often associated with hearing loss and ocular symptoms. ATS has been shown to be caused by COL4A5 mutations in its X-linked form and by COL4A3 and COL4A4 mutations in its autosomal forms. Methods. Five families with a suspicion of ATS were investigated both from a clinical and molecular point of view. COL4A3 and COL4A4 genes were analysed by DHPLC. Automated sequencing was performed to identify the underlying mutation. Results. Molecular analysis indicated that in all 5 cases the correct diagnosis was autosomal recessive ATS. In three families in which parental consanguinity clearly pinpointed to autosomal recessive ATS, we found COL4A4 homozygous mutations in two of them and COL4A3 homozygous mutation in the other one. In the remaining two families a differential diagnosis including X-linked ATS, autosomal recessive ATS and thin basement membrane nephropathy was considered. The molecular analysis demonstrated that the probands were genetic compounds for two different mutations in the COL4A4 gene pinpointing to the correct diagnosis of autosomal recessive ATS. Conclusions. A clinical evaluation of probands and their relatives of the five families carrying mutations in either the COL4A3 or the COL4A4 gene was carried out to underline the natural history of the autosomal recessive ATS. In addition, this paper stresses the complexity of the clinics and genetics of ATS and how a correct diagnosis is based on a combination of: (i) an in-depth clinical investigation; (ii) a detailed formal genetic analysis; (iii) a correct technical choice of the gene to be investigated; (iv) a correct technical choice of the family member to be included in the mutational screening. A correct diagnosis is the basis for an appropriate genetic counselling dealing with both the correct prognosis and the accurate recurrence risk for the patients and family members.

Plasma homocysteine, a new cardiovascular risk factor in both children and adults, is higher in chronic renal failure or kidney transplant patients. This alteration has been linked, in chronic renal failure, to plasma protein damage, represented by increased L-isoaspartyl residues. We measured plasma homocysteine levels and plasma protein damage in pediatric patients from four different Italian regions with conservatively treated renal failure; hemodialysis, continuous ambulatory peritoneal dialysis (CAPD), or transplants, to establish the presence of protein damage and the relative role of hyperhomocysteinemia.High performance liquid chromatography (HPLC) separation measured total plasma homocysteine levels, using precolumn derivatization with ammonium 7-fluorobenzo-2-oxa-1, 3-diazole-4-sulphonate (SBD-F). Plasma protein L-isoaspartyl residues were quantitated using human recombinant protein carboxyl methyl transferase (PCMT).In all patient groups, homocysteine levels were significantly higher with respect to the control (Control: 6.87 +/- 0.73 microM) conservatively treated, 14.19 +/- 1.73 microM; hemodialysis, 27.03 +/- 4.32 microM; CAPD, 22.38 +/- 3.73 microM; transplanted, 20.22 +/- 2.27 microM, p0.001 vs. control]. Plasma protein damage was significantly higher in conservatively treated, hemodialysis (HD) and CAPD patients, while in transplant patients it was no different from the control.We concluded that in pediatric patients of different Italian geographical origin, plasma homocysteine levels were significantly higher in all groups with respect to healthy children; therefore contributing to the elevated cardiovascular risk present in these patients. Plasma protein L-isoaspartyl content was higher in renal failure patients, but kidney transplant patients had normal levels, indicating that this kind of protein damage relates more to the toxic action of uremic retention solutes, than to plasma homocysteine levels.

Darbepoietin alfa (NESP) is a new long-acting erythropoietin, with a half-life 3 times longer than the old epoietins. In the present study, we evaluated the efficacy of NESP in a group of children on hemodialysis. Seven children, five male and two female, with a mean age of 11.5 +/- 3 years and a mean weight of 34.1 +/- 11 kg, were enrolled in the study. All had been treated for at least 6 months with epoietin alfa at a mean dose of 106 +/- 76 IU/kg 3 times/week i.v. They were then given NESP at a mean dose of 1.59 +/- 1.19 microg/kg once a week i.v., according to the suggested conversion index (weekly epoietin alfa dose/200=weekly NESP dose). Anemia was evaluated at the end of a dialysis session. This was especially important for children less compliant with water restriction. Serum ferritin and percentage transferrin saturation (TSAT) were also monitored, as were dialysis efficacy (Kt/V), blood pressure, and heparin requirements. Before starting the new treatment, all patients had an adequate mean hemoglobin (Hb) level (11.19 +/- 1.7 g/dl) and an adequate iron status (TSAT 24.2 +/- 11.5, serum ferritin 220 +/- 105 mg/dl). Five of the seven patients were also treated with intravenous ferric gluconate (10-20 mg/kg per week). Six children were on antihypertensive treatment. After the 1st month of treatment, we observed an excessive increase in Hb, 12.3 +/- 1.7 g/dl, (P0.05), with severe hypertension in the youngest two patients (Hb13 g/dl). A short discontinuation of the medication, followed by restarting at a decreased dosage, allowed us to continue with the treatment. At the 2nd month of follow-up, a mean plasma Hb level of 12.2 +/- 1.2 g/dl was observed, with a NESP mean dose of 0.79 +/- 0.4 microg/kg per week. Steady state was reached at 3 months, with a mean Hb of 11.8 +/- 1.4 g/dl and a mean NESP dose of 0.51 +/- 0.18 microg/kg per week (P0.05). These results persisted at 6 months of follow-up; only one child had a persistent increase in platelet level (373,000 vs. 555,000). Dialysis efficiency and heparin requirements during dialysis did not change significantly. The high efficacy of NESP allowed a consistent reduction in dosage. The suggested conversion index does not appear to be correct for pediatric patients. Our experience suggests that in this population the correct dose could be 0.25-0.75 microg/kg per week. Hypertension was the only major side effect reported. The influence of NESP on platelet proliferation needs to be further investigated. The single weekly administration of NESP could be effective and beneficial for both patients and clinicians.

Many factors have been proposed as predictors of poor renal prognosis in children with hemolytic uremic syndrome (HUS), but their role is still controversial. Our aim was to detect the most reliable early predictors of poor renal prognosis to promptly identify children at major risk of bad outcome who could eventually benefit from early specific treatments, such as plasmapheresis. Prognostic factors identifiable at onset of HUS were evaluated by survival analysis and a proportional hazard model. These included age at onset, prodromal diarrhea (D), leukocyte count, central nervous system (CNS) involvement, and evidence of Shiga toxin-producing Escherichia coli (STEC) infection. Three hundred and eighty-seven HUS cases were reported; 276 were investigated for STEC infection and 189 (68%) proved positive. Age at onset, leukocyte count, and CNS involvement were not associated with the time to recovery. Absence of prodromal D and lack of evidence of STEC infection were independently associated with a poor renal prognosis; only 34% of patients D(-)STEC(- )recovered normal renal function compared with 65%-76% of D(+)STEC(+), D(+)STEC(-) and D(-)STEC(+ )patients. In conclusion, absence of both D and evidence of STEC infection are needed to identify patients with HUS and worst prognosis, while D(-) but STEC(+) patients have a significantly better prognosis.

Congenital nephrotic syndrome of the Finnish type (CNF) is an autosomal recessive disorder mainly caused by mutations in the nephrin gene (NPHS1). The frequency of this gene is highest in Finland but the condition occurs in all populations, with and without Finnish ancestry. The NPHS1 gene is located in the chromosomal region 19q13.1 and consists of 29 exons.Polymerase chain reaction (PCR), restriction and sequence analyses were used to screen 15 CNF Italian patients for mutations in this gene.No Italian patients had the typical Finnish mutations, a 2bp deletion in exon 2 (Fin-major) and a nonsense mutation in exon 26 (Fin-minor). We found 13 mutations including deletions, insertions, nonsense and missense mutations. Seven of these have never been described before. We also found one nucleotide change in the promoter region and one common polymorphism. NPHS1 missense mutations were confirmed by analysis of a healthy control population.Our study provides further evidence that loss of function of the nephrin gene is the main cause of congenital nephrotic syndrome of the Finnish type in Italian patients.

A retrospective study on the use of plasma exchange in children with hemolytic-uremic syndrome was conducted to compare the renal outcome in treated and nontreated patients. Only children over 5 years of age were selected because they seem to be at major risk of bad renal prognosis. The evolution of renal function in the two populations is not significantly different, but chronic renal failure (clearance60 mL/min/1.73 m2) and end-stage renal failure were present only in untreated patients.

Clinical or biochemical findings were reevaluated in 34 pediatric patients with primary renal tubular hypokalemic metabolic alkalosis. The patients were subdivided into two groups. Bartter syndrome (primary renal tubular hypokalemic metabolic alkalosis with normocalciuria or hypercalciuria) was diagnosed in 18 patients with molar urinary calcium/creatinine ratios greater than 0.20, and Gitelman syndrome (primary renal tubular hypokalemic metabolic alkalosis with magnesium deficiency and hypocalciuria) was diagnosed in 16 patients with molar urinary calcium/creatinine ratios less than or equal to 0.20 and plasma magnesium levels less than 0.75 mmol/L. Some clinically important differences between the groups were observed. Patients with Bartter syndrome were often born after pregnancies complicated by polyhydramnios (8/18) or premature delivery (7/18) and had short stature (11/18) or polyuria, polydipsia, and a tendency to dehydration (16/18) during infancy (12/18) or before school age (18/18). Patients with Gitelman syndrome had tetanic episodes (12/16) or short stature (3/16) at school age (14/16). We conclude that the Bartter and Gitelman syndromes represent two distinct variants of primary renal tubular hypokalemic metabolic alkalosis and are easily distinguished on the basis of urinary calcium levels.