Marisa Giani

Advantages of cyclosporine as sole immunosuppressive agent in children with transplanted kidneys.

A prospective study of intentional stopping of steroids 6 months after transplantation was done with 29 pediatric renal transplant recipients with a mean age of 10.4±3.4 years. Immunosuppression consisted of cyclosporine and methylprednisolone. We stopped giving MP to 24 children: to twenty after six months, four after 11–20 months. “Crude graft survival” was 97% during a mean follow-up of 36.7±15 months. The rejection rate was 48% during the first 6 months and 29% in the period after stopping MP. At present, 20/24 children (83%) have remained on CsA alone (18 patients) or CsA and azathioprine (2 patients) during a mean follow-up of 30±17 months. CsA nephrotoxicity occurred in 20.6% of patients, gum hypertrophy in 45%, hypertrichosis in 24%, and neurological symptoms in two patients (6.8%). Linear growth significantly improved after stopping MP: mean catch-up growth for prepuberal children 1.38 height standard deviation score (HSDS) and for pubertal children 1.6 HSDS. Bone age did not increase more rapidly than chronologic age. Weight/height index (W/HI) also improved. There was also a significant reduction in the use of antihypertensive drugs. Calculated glomerular filtration rate was decreased, though not significantly, after stopping MP. Thus, when graft survival is good, stopping corticosteroids corrects the major handicap of children with irreversible uremia—the poor linear growth—and improves the W/HI and control of arterial pressure. Longer follow-up periods are necessary to exclude significant worsening of renal function and an increased incidence of chronic rejection after stopping the steroid.

Urine erythrocyte morphology in patients with microscopic haematuria caused by a glomerulopathy

The evaluation of urinary erythrocyte morphology (UEM) has been proposed for patients with isolated microscopic haematuria (IMH) to early orientate the diagnosis towards a glomerular or a nonglomerular disease. However, to date, the role of this test in patients with IMH has very rarely been investigated. Sixteen patients (ten children, six adults) with persistent IMH classified as glomerular on the basis of repeated UEM evaluations (55 urine samples, two to eight per patient) were submitted to renal biopsy. This showed a glomerular disease in 14/16 patients (87.5%) (nine thin basement membrane disease; three Alport syndrome; two other), whereas in two patients, no abnormalities were found. Of four microscopic criteria investigated to define a IMH as glomerular, >80% dysmorphic erythrocytes were not found in any sample, ≥40% dysmorphic erythrocytes alone were seen in seven samples (12.7%), ≥5% acanthocytes alone in 15 samples (27.3%) and erythrocytic casts in six samples (10.9%). There was ≥40% dysmorphic erythrocytes associated with ≥5% acanthocytes in 25 samples (45.5%). Sensitivity and positive predictive values in diagnosing a glomerular haematuria were 59.2% and 90.6%, respectively, for ≥40% dysmorphic erythrocytes, 69.4% and 85% for ≥5% acanthocytes/G1 cells and 12.2% and 100% for erythrocytic casts. Our findings demonstrate that the evaluation of UEM is useful to identify patients with an IMH of glomerular origin.

Simultaneous Mutations in the CLCNKB and SLC12A3 Genes in Two Siblings with Phenotypic Heterogeneity in Classic Bartter Syndrome

Two siblings (brother and sister) with renal tubular hypokalemic alkalosis underwent clinical, biochemical and molecular investigations. Although the biochemical findings were similar (including hypokalemia, metabolic alkalosis, hyperreninemia, hyperaldosteronism and normal blood pressure), the clinical findings were different: the boy, who also presented syndromic signs, developed glomerular proteinuria and renal biopsy revealed focal segmental glomerular sclerosis; the girl showed the typical signs of classic Bartter syndrome. As described in a previous paper, a heterozygous mutation (frameshift 2534delT) was demonstrated in the gene encoding the thiazide-sensitive NaCl co-transporter (SLC12A3) of the distal convoluted tubule; the second molecular analysis revealed a compound heterozygous mutation (A61D/V149E) in the CLCNKB chloride channel gene in both subjects, inherited in trans from the parents. The children were finally diagnosed as having classic Bartter syndrome. These cases represent the first report of the simultaneous presence of heterozygous and compound heterozygous mutations in the SLC12A3 and CLCNKB genes, both of which are involved in renal salt losing tubulopathies, and confirm previous observations regarding classic Bartter syndrome phenotype variability in the same kindred.

Successful medical treatment of EBV smooth muscle tumor in a renal transplant recipient.

Belingheri M, Comoli P, Locatelli F, Baldanti F, Martina V, Giani M, Ferraresso M, Cro L, Edefonti A, Ghio L. Successful medical treatment of EBV smooth muscle tumor in a renal transplant recipient.
Pediatr Transplantation 2010: 14:E101–E104.

Alport syndrome cold cases: Missing mutations identified by exome sequencing and functional analysis

Alport syndrome (AS) is an inherited progressive renal disease caused by mutations in COL4A3, COL4A4, and COL4A5 genes. Despite simultaneous screening of these genes being widely available, mutation detection still remains incomplete in a non-marginal portion of patients. Here, we applied whole-exome sequencing (WES) in 3 Italian families negative after candidate-gene analyses. In Family 1, we identified a novel heterozygous intronic variant (c.2245-40A>G) -outside the conventionally screened candidate region for diagnosis- potentially disrupting COL4A5 exon29 splicing. Using a minigene-based approach in HEK293 cells we demonstrated that this variant abolishes exon29 branch site, causing exon skipping. Moreover, skewed X-inactivation of the c.2245-40A>G allele correlated with disease severity in heterozygous females. In Family 2, WES highlighted a novel COL4A5 hemizygous missense mutation (p.Gly491Asp), which segregates with the phenotype and impacts on a highly-conserved residue. Finally, in Family 3, we detected a homozygous 24-bp in-frame deletion in COL4A3 exon1 (NM_000091.4:c.30_53del:p.Val11_Leu18del or c.40_63del24:p.Leu14_Leu21del), which is ambiguously annotated in databases, although it corresponds to a recurrent AS mutation. Functional analyses showed that this deletion disrupts COL4A3 signal peptide, possibly altering protein secretion. In conclusion, WES -together with functional studies- was fundamental for molecular diagnosis in 3 AS families, highlighting pathogenic variants that escaped previous screenings.

INFLUENCE OF HEMOFILTRATION ON NITROGEN BALANCE AND GROWTH RATE IN CHILDREN ON END STAGE RENAL DISEASE

Comparative influence of Hemodialysis (HD) and Hemofiltration (HF) on nitrogen balance (Nb) and growth rate (GR) was investigated in 8 children, 3 males and 5 females, 11.25±2.9 years old.Children were treated first with HD for 25.7±11.9 months and afterwards with HF for 19.5±4.1 months. Nb was evaluated every 2 months by the difference between dietary protein intake (DPl) and protein catabolic rate (PCR), determined by urea kinetics. GR was assessed according with Tanner over a full year period. Results: mean and (SD)In conclusion, HF appears to improve growth of children with end stage renal failure previously treated with HD,as indicated by both Nb and GR data.