Prescription of drugs blocking the renin-angiotensin system in Italian children.

Little is known about the prescription pattern of antihypertensive drugs for children with impaired kidney function. We have therefore documented the use of antihypertensive drugs in this patient group by evaluating the Italian pediatric population-based registry of patients with chronic kidney disease on conservative treatment (ItalKid) from 1995 to 2003. In 1995, prescriptions written for antihypertensive drugs for use by children were approximately equally divided among drugs blocking the renin-angiotensin system and calcium channel blockers (38 vs. 43% of all prescriptions), followed by beta-blockers and diuretics (15 and 4%, respectively). During subsequent years the proportion of prescriptions for drugs blocking the renin-angiotensin system increased (2003: 61%; p<0.001) and that of calcium channel blockers decreased (2003: 18%, p<0.001). In 1995, blockers of the renin-angiotensin system were prescribed, either as monotherapy or in combination, in 53% of the patients, but the relative frequency of the patients prescribed these drugs increased up to 83% in 2003 (p<0.0005). In conclusion, physicians caring for Italian children with impaired kidney function are increasingly prescribing drugs blocking the renin-angiotensin system.

A particular phenotype in a girl with aldosterone synthase deficiency.

Aldosterone synthase deficiency (ASD) usually presents in infancy as a life-threatening electrolyte imbalance. A 4-wk-old child of unrelated parents was examined for failure to thrive and salt-wasting. Notable laboratory findings were hyperkalemia, high plasma renin, and low-normal aldosterone levels. Urinary metabolite ratios of corticosterone/18-hydroxycorticosterone and 18-hydroxycorticosterone/aldosterone were intermediate between ASD type I and type II. Sequence analysis of CYP11B2, the gene encoding aldosterone synthase (P450c11AS), revealed that the patient was a compound heterozygote carrying a previously described mutation located in exon 4 causing a premature stop codon (E255X) and a further, novel mutation in exon 5 that also causes a premature stop codon (Q272X). The patient's unaffected father was a heterozygous carrier of the E255X mutation, whereas the unaffected mother was a heterozygous carrier of the Q272X mutation. Therefore, the patient's CYP11B2 encodes two truncated forms of aldosterone synthase predicted to be inactive because they lack critical active site residues as well as the heme-binding site. This case of ASD is of particular interest because despite the apparent lack of aldosterone synthase activity, the patient displays low-normal aldosterone levels, thus raising the question of its source.

Voiding cystourethrosonography for the diagnosis of vesicoureteral reflux in a developing country.

The primary causes of renal insufficiency in Albanian children are reflux nephropathy and obstructive uropathies. The poor availability and technical quality of conventional radiological imaging in detecting vesicoureteral reflux (VUR) and lower urinary tract obstruction stimulated this pilot study, with the aim of evaluating the diagnostic efficacy of voiding cystourethrosonography (CUS). The study included 34 patients (aged 0.1-14 years) with acute pyelonephritis, 7 of whom already had renal insufficiency. In 22 patients voiding cystourethrography (VCUG) was also performed and a diagnostic concordance of 66.6% between the two techniques was found. Overall CUS showed a sensitivity superior to VCUG in detecting VUR, partly due to technical problems in performing the fluoroscopic examination. For the same reasons, VCUG missed 1 diagnosis of posterior urethral valves, while CUS correctly identified all 4 patients with this diagnosis. In 34 patients, CUS diagnosed 55 cases of grade II-V VUR and 11 urinary tract malformations; 12 patients underwent surgical intervention, some of them on the basis of CUS only. The follow-up of 31-81 (mean 53) months after CUS was completed by 94% of patients, excluding complications due to missed diagnoses. CUS was demonstrated to be a safe, reliable, and reproducible imaging modality without X-ray hazards that could be useful in developing countries. The potential limiting factors of the technique include the operator's training and experience and the costs of the contrast medium.

Different inactivating mutations of the mineralocorticoid receptor in fourteen families affected by type I pseudohypoaldosteronism.

We have analyzed the human mineralocorticoid receptor (hMR) gene in 14 families with autosomal dominant or sporadic pseudohypoaldosteronism (PHA1), a rare form of mineralocorticoid resistance characterized by neonatal renal salt wasting and failure to thrive. Six heterozygous mutations were detected. Two frameshift mutations in exon 2 (insT1354, del8bp537) and one nonsense mutation in exon 4 (C2157A, Cys645stop) generate truncated proteins due to premature stop codons. Three missense mutations (G633R, Q776R, L979P) differently affect hMR function. The DNA binding domain mutant R633 exhibits reduced maximal transactivation, although its binding characteristics and ED(50) of transactivation are comparable with wild-type hMR. Ligand binding domain mutants R776 and P979 present reduced or absent aldosterone binding, respectively, which is associated with reduced or absent ligand-dependent transactivation capacity. Finally, P979 possesses a transdominant negative effect on wild-type hMR activity, whereas mutations G633R and Q776R probably result in haploinsufficiency in PHA1 patients. We conclude that hMR mutations are a common feature of autosomal dominant PHA1, being found in 70% of our familial cases. Their absence in some families underscores the importance of an extensive investigation of the hMR gene and the role of precise diagnostic procedures to allow for identification of other genes potentially involved in the disease.

COL4A3/COL4A4 mutations: from familial hematuria to autosomal-dominant or recessive Alport syndrome.

UNLABELLED: COL4A3/COL4A4 mutations: From familial hematuria to autosomal-dominant or recessive Alport syndrome. BACKGROUND: Mutations of the type IV collagen COL4A5 gene cause X-linked Alport syndrome (ATS). Mutations of COL4A3 and COL4A4 have been reported both in autosomal-recessive and autosomal-dominant ATS, as well as in benign familial hematuria (BFH). In the latter conditions, however, clinical features are less defined, few mutations have been reported, and other genes and non-genetic factors may be involved. METHODS: We analyzed 36 ATS patients for COL4A3 and COL4A4 mutations by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and direct sequencing. Sporadic patients who had tested negative for COL4A5 mutations were included with typical cases of autosomal recessive ATS to secure a better definition of the phenotype spectrum. RESULTS: We identified seven previously undescribed COL4A3 mutations: in two genetic compounds and three heterozygotes, and one in COL4A4. In agreement with the literature, some of the mutations of compound heterozygotes were associated with microhematuria in healthy heterozygous relatives. The mutations of heterozygous patients are likely dominant, since no change was identified in the second allele even by sequencing, and they are predicted to result in shortened or abnormal chains with a possible dominant-negative effect. In addition, both genes showed rare variants of unclear pathogenicity, and common polymorphisms that are shared in part with other populations. CONCLUSIONS: This study extends the mutation spectrum of COL4A3 and COL4A4 genes, and suggests a possible relationship between production of abnormal COL IV chains and dominant expression of a continuous spectrum of phenotypes, from ATS to BFH.

Role of ultrasound in the imaging of posterior urethral valves.

The intrinsic abnormalities of male urethra causing urinary obstruction are frequently responsible for renal insufficiency, sometimes present at birth. The rare but typical malformations such as the posterior urethral valves represent major deviations from the normal embryonic development, and require prompt identification and surgical correction. Since the symptoms and signs that suggest the presence of abnormalities of the urinary tract are sometimes vague and nonspecific, in the majority of cases voiding cystourethrography (VCUG) performed in children depicts a normal urethra. To prevent the X-ray hazard, voiding cystourethrosonography (VCUS), i.e. contrast-enhanced dynamic ultrasonography of the urinary tract, was introduced. This article reviews the possibilities, advantages and limitations of this new ultrasonographic technique performed consecutively in 231 0-15 year-old male patients, whose normal and obstructive urethral patterns were clearly visualized; the latter were all confirmed by VCUG and interventional cystourethroscopy.