Mutations in kelch-like 3 and cullin 3 cause hypertension and electrolyte abnormalities.

Hypertension affects one billion people and is a principal reversible risk factor for cardiovascular disease. Pseudohypoaldosteronism type II (PHAII), a rare Mendelian syndrome featuring hypertension, hyperkalaemia and metabolic acidosis, has revealed previously unrecognized physiology orchestrating the balance between renal salt reabsorption and K(+) and H(+) excretion. Here we used exome sequencing to identify mutations in kelch-like 3 (KLHL3) or cullin 3 (CUL3) in PHAII patients from 41 unrelated families. KLHL3 mutations are either recessive or dominant, whereas CUL3 mutations are dominant and predominantly de novo. CUL3 and BTB-domain-containing kelch proteins such as KLHL3 are components of cullin-RING E3 ligase complexes that ubiquitinate substrates bound to kelch propeller domains. Dominant KLHL3 mutations are clustered in short segments within the kelch propeller and BTB domains implicated in substrate and cullin binding, respectively. Diverse CUL3 mutations all result in skipping of exon 9, producing an in-frame deletion. Because dominant KLHL3 and CUL3 mutations both phenocopy recessive loss-of-function KLHL3 mutations, they may abrogate ubiquitination of KLHL3 substrates. Disease features are reversed by thiazide diuretics, which inhibit the Na-Cl cotransporter in the distal nephron of the kidney; KLHL3 and CUL3 are expressed in this location, suggesting a mechanistic link between KLHL3 and CUL3 mutations, increased Na-Cl reabsorption, and disease pathogenesis. These findings demonstrate the utility of exome sequencing in disease gene identification despite the combined complexities of locus heterogeneity, mixed models of transmission and frequent de novo mutation, and establish a fundamental role for KLHL3 and CUL3 in blood pressure, K(+) and pH homeostasis.

Urinary exosomes in the diagnosis of Gitelman and Bartter syndromes.

BACKGROUND: Gitelman syndrome (GS) and Bartter syndrome (BS) are hereditary salt-losing tubulopathies (SLTs) resulting from defects of renal proteins involved in electrolyte reabsorption, as for sodium-chloride cotransporter (NCC) and furosemide-sensitive sodium-potassium-chloride cotransporter (NKCC2) cotransporters, affected in GS and BS Type 1 patients, respectively. Currently, definitive diagnosis is obtained through expensive and time-consuming genetic testing. Urinary exosomes (UE), nanovesicles released by every epithelial cell facing the urinary space, represent an ideal source of markers for renal dysfunction and injury, because UE molecular composition stands for the cell of origin. On these assumptions, the aim of this work is to evaluate the relevance of UE for the diagnosis of SLTs. METHODS: UE were purified from second morning urines collected from 32 patients with genetically proven SLTs (GS, BS1, BS2 and BS3 patients), 4 with unclassified SLTs and 22 control subjects (age and sex matched). The levels of NCC and NKCC2 were evaluated in UE by SDS-PAGE/western blotting with specific antibodies. RESULTS: Due to their location on the luminal side of tubular cells, NCC and NKCC2 are well represented in UE proteome. The NCC signal is significantly decreased/absent in UE of Gitelman patients compared with control subjects (Mann-Whitney t-test, P < 0.001) and, similarly, the NKCC2 in those of Bartter type 1 (P < 0.001). The difference in the levels of the two proteins allows recognition of Gitelman and Bartter type 1 patients from controls and, combined with clinical data, from other Bartter patients. Moreover, the receiver operating characteristic curve analysis using UE NCC densitometric values showed a good discriminating power of the test comparing GS patients versus controls and BS patients (area under the curve value = 0.92; sensitivity 84.2% and specificity 88.6%). CONCLUSIONS: UE phenotyping may be useful in the diagnosis of GS and BS, thus providing an alternative/complementary, urine-based diagnostic tool for SLT patient recognition and a diagnostic guidance in complex cases.

Best practice guidelines for idiopathic nephrotic syndrome: recommendations versus reality.

BACKGROUND: The optimal therapeutic regimen for managing childhood idiopathic nephrotic syndrome (INS) is still under debate. We have evaluated the choice of steroid regimen and of symptomatic treatment adopted by pediatricians and pediatric nephrologists in a large number of centers as the first step towards establishing a shared protocol METHODS: This was a multicenter, retrospective study. A total of 231 children (132 admitted to pediatric units) aged 6 months to <15 years who presented with onset of nephrotic syndrome to 54 pediatric units and six pediatric nephrology units in Italy between 2007 and 2009 were eligible for entry into the study. RESULTS: Median steroid dosing was 55 (range 27-75) mg/m(2)/day. The overall median cumulative dose regimen for the first episode was 3,440 (1,904-6,035) mg/m(2), and the median duration of the therapeutic regimen was 21 (9-48) weeks. The total duration and cumulative steroid dose were significantly higher in patients treated by pediatricians than in those treated by pediatric nephrologists (p = 0.001 and p = 0.008). Among the patient cohort, 55, 64 and 22 % received albumin infusions, diuretics and acetyl salicylic acid treatment, respectively, but the laboratory and clinical data did not differ between children treated or not treated with symptomatic drugs. Albumin and diuretic use did not vary between patients in pediatric units and those in pediatric nephrology units. CONCLUSIONS: This study shows major differences in steroid and symptomatic treatment of nephrotic syndrome by pediatricians and pediatric nephrologists. As these differences can influence the efficacy of the treatments and the appearance of side-effects, shared guidelines and their implementation through widespread educational activities are necessary.

Ureteral or vesical involvement in Henoch-Schönlein syndrome: a systematic review of the literature.

BACKGROUND: Little information is available on ureteral or vesical involvement in Henoch-Schönlein syndrome. To determine the features of this condition we performed a formal analysis of peer-reviewed scientific literature on this topic. METHODS: The US National Library of Medicine database was used as the data source. All articles published as full-length articles or letters were collected. Reports published in languages other than English, French, German, Italian or Spanish were not considered. RESULTS: We analyzed 32 reports describing 35 cases (24 male and 11 female subjects aged between 3.5 and 63, median 7.0 years) with ureteral (n = 30), vesical (n = 4), or both ureteral and vesical involvement (n = 1). The presentation included colicky abdominal pain, macroscopic hematuria (sometimes containing blood clots), urinary tract infection or urinary retention. The diagnosis of ureteral involvement was often fortuitous. Patients with vesical involvement were managed conservatively. However, the majority of those with ureteral involvement were managed surgically. CONCLUSIONS: Ureteral or vesical involvement is unusual and likely underappreciated in Henoch-Schönlein syndrome. Improved recognition and wider appreciation of this involvement can help to avoid associated morbidity. Management must be individualized for each patient. A multidisciplinary approach may be of value in planning medical treatment, surgical intervention, and follow-up.

Phosphate homeostasis in Bartter syndrome: a case-control study.

BACKGROUND: Bartter patients may be hypercalciuric. Additional abnormalities in the metabolism of calcium, phosphate, and calciotropic hormones have occasionally been reported. METHODS: The metabolism of calcium, phosphate, and calciotropic hormones was investigated in 15 patients with Bartter syndrome and 15 healthy subjects. RESULTS: Compared to the controls, Bartter patients had significantly reduced plasma phosphate {mean [interquartile range]:1.29 [1.16-1.46] vs. 1.61 [1.54-1.67] mmol/L} and maximal tubular phosphate reabsorption (1.16 [1.00-1.35] vs. 1.41 [1.37-1.47] mmol/L) and significantly increased parathyroid hormone (PTH) level (6.1 [4.5-7.7] vs. 2.8 [2.2-4.4] pmol/L). However, patients and controls did not differ in blood calcium, 25-hydroxyvitamin D, alkaline phosphatase, and osteocalcin levels. In patients, an inverse correlation (P < 0.05) was noted between total plasma calcium or glomerular filtration rate and PTH concentration. A positive correlation was also noted between PTH and osteocalcin concentrations (P < 0.005), as well as between chloriduria or natriuria and phosphaturia (P < 0.001). No correlation was noted between calciuria and PTH concentration or between urinary or circulating phosphate and PTH. CONCLUSIONS: The results of this study demonstrate a tendency towards renal phosphate wasting and elevated circulating PTH levels in Bartter patients.

Transient benign hyperphophatasemia.

BACKGROUND AND AIM: Sometimes, a temporary increase in alkaline phosphatase level is found in healthy infants and toddlers without evidence of liver or bone disease. The condition is customarily termed transient benign hyperphosphatasemia of infancy and early childhood. Most textbooks do not refer to the condition. The aim of the study was to promote broader awareness of transient benign hyperphosphatasemia. METHODS: We completed a systematic review of the literature using the principles underlying the UK Economic and Social Research Council guidance on the conduct of narrative synthesis and the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. RESULTS: The 142 reports retained for analysis included 813 cases (male:female ratio 1.1:1.0): 80 in subjects older than 18 years and 733 in subjects 18 years or younger. The alkaline phosphatase ratio, calculated by dividing the measured level by the upper limit of normal, was ≥5.0 in ≈70% and the duration of the elevation was ≤4 months in 80% of the cases. Transient benign hyperphosphatasemia often followed a benign infection, but available data fail to demonstrate a causal link. The prevalence of transient benign hyperphosphatasemia ranged from 1.1% to 3.5% in infants 2 to 24 months of age. CONCLUSIONS: Transient benign hyperphosphatasemia is likely the most common cause of hyperphosphatasemia among healthy infants and toddlers. Sometimes it also occurs in older children and adults, indicating that the traditional term transient benign hyperphosphatasemia of infancy and early childhood may not be correct. The elevation in alkaline phosphatase persists for >4 months in ≈20% of the cases. Recognition of this benign condition is crucial to avoid unnecessary investigations.

Renal phosphate handling in Gitelman syndrome--the results of a case-control study.

BACKGROUND: Patients with Gitelman syndrome, a hereditary salt-wasting tubulopathy, have loss-of-function mutations in the SLC12A3 gene coding for the thiazide-sensitive sodium chloride co-transporter in the distal convoluted tubule. Since the bulk of filtered phosphate is reabsorbed in the proximal tubule, renal phosphate wasting is considered exceptional in Gitelman syndrome. METHODS: We investigated the renal handling of inorganic phosphate in 12 unselected Italian patients affected with Gitelman syndrome (5 females and 7 males, aged 6.0-18 years, median age 12 years) and in 12 healthy subjects matched for gender and age (controls). The diagnosis of Gitelman syndrome among the patients had been made clinically and confirmed by molecular biology studies. RESULTS: The biochemical hallmarks of Gitelman syndrome, namely hypochloremia, hypokalemia, hypomagnesemia, increased urinary excretion of sodium, chloride, potassium and magnesium and reduced urinary excretion of calcium, were present in the 12 patients. In addition, both the plasma inorganic phosphate concentration (median and interquartile range: 1.28 [1.12-1.36] vs. 1.61 [1.51-1.66)] mmol/L) and the maximal tubular reabsorption of inorganic phosphate (1.08 [0.99-1.22] vs. 1.41 [1.38-1.47] mmol/L) were significantly lower (P < 0.001) in Gitelman patients than in control subjects. Circulating levels of 25-hydroxyvitamin D, intact parathyroid hormone and osteocalcin were similar in patients and controls. CONCLUSIONS: The results of our case-control study disclose a hitherto unrecognized tendency towards renal phosphate wasting with mild to moderate hypophosphatemia in Gitelman syndrome.

Living with Gitelman disease: an insight into patients' daily experiences.

BACKGROUND: Gitelman disease presents with musculoskeletal complaints and fatigue. Surprisingly, there is no clear-cut correlation between biochemical abnormalities and symptoms. METHODS: Starting from the hypothesis that the way patients comprehend their illness within their sociocultural frameworks reflects on their way of adapting to it, this study investigated how adult patients experience the disease in everyday life. We conducted a qualitative analysis based on interviews with 12 patients. Interviews were audio recorded, fully transcribed and analyzed using the constant comparative method described by Strauss and Corbin. RESULTS: A typology of the experiences emerged from the data and was tested on each transcript with an explicit search for disconfirming cases. Patients fell into four main groups: (i) those considering Gitelman disease a disabling illness, (ii) those considering it a normalized illness, (iii) those considering it a different normality and (iv) those considering it an episodic disability. Each pattern of experience was characterized by particular (i) ways of interpreting symptoms (ii) ways of managing Gitelman disease in everyday life, (iii) general lifestyles and (iv) risks for the patient's psychosocial life. CONCLUSIONS: These findings suggest that health care providers should take advantage of considering patients' own perception of the disease in order to adjust the care and advice provided.

Renal salt-wasting syndrome in children with intracranial disorders.

Hypotonic hyponatremia, a serious and recognized complication of any intracranial disorder, results from extra-cellular fluid volume depletion, inappropriate anti-diuresis or renal salt-wasting. The putative mechanisms by which intracranial disorders might lead to renal salt-wasting are either a disrupted neural input to the kidney or the elaboration of a circulating natriuretic factor. The key to diagnosis of renal salt-wasting lies in the assessment of extra-cellular volume status: the central venous pressure is currently considered the yardstick for measuring fluid volume status in subjects with intracranial disorders and hyponatremia. Approximately 110 cases have been reported so far in subjects ≤18 years of age (male: 63%; female: 37%): intracranial surgery, meningo-encephalitis (most frequently tuberculous) or head injury were the most common underlying disorders. Volume and sodium repletion are the goals of treatment, and this can be performed using some combination of isotonic saline, hypertonic saline, and mineralocorticoids (fludrocortisone). It is worthy of a mention, however, that some authorities contend that cerebral salt wasting syndrome does not exist, since this diagnosis requires evidence of a reduced arterial blood volume, a concept but not a measurable variable.

The mutation c.1196_1202dup7bp (p.Ser402X) in the SLC12A3 gene clusters in Italian Gitelman syndrome patients and reflects the presence of a common ancestor.

BACKGROUND: Inactivating mutations in the SLC12A3 gene are the main cause of Gitelman's syndrome (GS), a renal tubular disorder inherited as an autosomal recessive trait. In our cohort of patients, we identified 11 probands from 11 apparently unrelated Italian families that carry the c.1196_1202dup7bp mutation, which appears to be more frequent than other mutations in Italian GS patients. Therefore, we characterized in greater detail the SLC12A3 locus and its vicinity in those patients that carry this mutation in order to detect a possible shared haplotype. Three further probands characterized in France, carrying the same mutation, were also included in this study. METHODS: Sequence or fragment analyses were carried out to investigate seven intragenic polymorphisms (rs3217425, rs3816119, rs2304483, rs2278490, rs2278489, rs2289116 and rs2289115) that flank the mutation, as well as two extragenic markers, D16S3071 and D16S3057, flanking the SLC12A3 locus in the 5' and 3' termini, respectively. RESULTS: A shared haplotype co-segregates with the mutation both in Italian and French probands. Moreover, all the Italian families originate from a restricted area of Italy. Likewise, the French probands come from an area of France close to the north of Italy. CONCLUSION: It is likely that the c.1196_1202dup7bp mutation in the SLC12A3 gene reflects the presence of a common ancestor in an area covering the northern-central part of Italy and eastern France. A modified genotyping strategy for GS patients originating from this area has to be considered.

Acute hemorrhagic edema of young children: a concise narrative review.

Acute hemorrhagic edema of young children is an uncommon but likely underestimated cutaneous leukocytoclastic vasculitis. The condition typically affects infants 6-24 months of age with a history of recent respiratory illness with or without course of antibiotics. The diagnosis is made in children, mostly nontoxic in appearance, presenting with nonpruritic, large, round, red to purpuric plaques predominantly over the cheeks, ears, and extremities, with relative sparing of the trunk, often with a target-like appearance, and edema of the distal extremities, ears, and face that is mostly non-pitting, indurative, and tender. In boys, the lesions sometimes involve the scrotum and, more rarely, the penis. Fever, typically of low grade, is often present. Involvement of body systems other than skin is uncommon, and spontaneous recovery usually occurs within 6-21 days without sequelae. In this condition, laboratory tests are non-contributory: total blood cell count is often normal, although leukocytosis and thrombocytosis are sometimes found, clotting studies are normal, erythrocyte sedimentation rate and C-reactive protein test are normal or slightly elevated, complement level is normal, autoantibodies are absent, and urinalysis is usually normal. Experienced physicians rapidly consider the possible diagnosis of acute hemorrhagic edema when presented with a nontoxic young child having large targetoid purpuric lesions and indurative swelling, which is non-pitting in character, and make the diagnosis either on the basis of clinical findings alone or supported by a skin biopsy study.

Long-term follow-up of patients with Bartter syndrome type I and II.

BACKGROUND: Little information is available on a long-term follow-up in Bartter syndrome type I and II. METHODS: Clinical presentation, treatment and long-term follow-up (5.0-21, median 11 years) were evaluated in 15 Italian patients with homozygous (n = 7) or compound heterozygous (n = 8) mutations in the SLC12A1 (n = 10) or KCNJ1 (n = 5) genes. RESULTS: Thirteen new mutations were identified. The 15 children were born pre-term with a normal for gestational age body weight. Medical treatment at the last follow-up control included supplementation with potassium in 13, non-steroidal anti-inflammatory agents in 12 and gastroprotective drugs in five patients. At last follow-up, body weight and height were within normal ranges in the patients. Glomerular filtration rate was <90 mL/min/1.73 m(2) in four patients (one of them with a pathologically increased urinary protein excretion). In three patients, abdominal ultrasound detected gallstones. The group of patients with antenatal Bartter syndrome had a lower renin ratio (P < 0.05) and a higher standard deviation score (SDS) for height (P < 0.05) than a previously studied group of patients with classical Bartter syndrome. CONCLUSIONS: Patients with Bartter syndrome type I and II tend to present a satisfactory prognosis after a median follow-up of more than 10 years. Gallstones might represent a new complication of antenatal Bartter syndrome.

Vasculitides associated with IgG antineutrophil cytoplasmic autoantibodies in childhood.

Immunoglobulin (Ig)G antineutrophil cytoplasmic autoantibodies are causally associated with necrotizing vasculitides that are characterized immunopathologically by little or no deposition of immunoreactants, such as Wegener granulomatosis, microscopic polyangiitis, Churg-Strauss angiitis, "renal-limited" vasculitis and a number of drug-induced vasculitides. Clinical routine testing targets the antigens myeloperoxidase and proteinase 3. However, in all of the conditions mentioned, the renal histopathologic findings are indistinguishable. Churg-Strauss angiitis (characterized by necrotizing vasculitis, granulomatous inflammation and tissue eosinophilia), Wegener granulomatosis (characterized by necrotizing vasculitis and granulomatous inflammation) and microscopic polyangiitis (characterized by necrotizing vasculitis) often present with fever, weight loss and a multisystem involvement (ear, nose, throat, lung, eyes, peripheral nerve and heart). Fifty years ago these conditions were very often fatal within 6 months of diagnosis. The introduction of corticosteroids and cyclophosphamide has resulted in a dramatic clinical benefit. Patients who develop treatment-related morbidity can be switched from cyclophosphamide to azathioprine after achieving remission. In patients with less severe disease, methotrexate achieves remission with a success rate similar to that of cyclophosphamide. Plasma exchange, in association with immunosuppression, is likely to be a beneficial therapy for patients with severe kidney disease or pulmonary hemorrhage.

Early appearance of hypokalemia in Gitelman syndrome.

Inactivating mutations in the SLC12A3 gene that encodes the thiazide-sensitive co-transporter causes Gitelman syndrome. The main features of this syndrome include normal or low blood pressure, hypokalemia, metabolic alkalosis, hypomagnesemia, hypocalciuria, and hyperreninemia. These patients are at low risk for preterm birth and do not present with symptoms before school age. As a consequence, the condition is usually diagnosed in late childhood or in adult life. We report on four patients, two pairs of prematurely born twins, in whom hypokalemia was demonstrated early in life. In these children, a tendency towards hypokalemia was first noted during the third week of life. Overt hypokalemia subsequently appeared associated with normal blood pressure, hypochloremia, hyperreninemia, and an inappropriately high fractional excretion of potassium and chloride. Molecular biology studies failed to detect mutations in the SLC12A1, KCNJ1, and CLCNKB genes responsible for the Bartter syndromes type I, II and III, respectively. Compound heterozygous mutations in the SLC12A3 gene were detected in both pairs of twins: a frameshift mutation in exon 10 (c.1196_1202dup7bp), leading to the truncated protein p.Ser402X, and a missense mutation in exon 11, p.Ser475Cys (c.1424C>G) in the first pair; two missense mutations, p.Thr392Ile (c.1175C>T) in exon 9 and p.Ser615Leu in exon 15 (c.1844C>T), in the second pair. In conclusion, the diagnosis of Gitelman syndrome deserves consideration in infants with unexplained hypokalemia.

Cardiac arrhythmias and rhabdomyolysis in Bartter-Gitelman patients.

Recent data demonstrate that patients affected with hypokalemic salt-losing tubulopathies are prone to acute cardiac arrhythmias and rhabdomyolysis. The tendency to these potentially fatal complications is especially high if chronic hypokalemia is severe, in patients with diarrhea, vomiting or a prolonged QT interval on standard electrocardiography, in patients on drug management with compounds prolonging the electrocardiographic QT interval (including antiarrhythmic agents, some antihistamines, macrolides, antifungals, psychotropics, beta2-adrenergic agonists or cisapride), following acute alcohol abuse and during exercise. Cardiac arrhythmias and rhabdomyolysis occur with sufficient frequency in hypokalemic salt-losing tubulopathies to merit wider awareness of their presence and the preparation of specific prevention and management recommendations.

Hypokalemic rhabdomyolysis in congenital tubular disorders: a case series and a systematic review.

Hypokalemia is a recognized cause of rhabdomyolysis but very few reports document its association with inborn renal tubular disorders. We report our experience with hypokalemic rhabdomyolysis in 5 pediatric patients affected by inborn renal tubular disorders and the results of a careful review of the literature disclosing 9 further cases for a total of 14 patients (8 male and 6 female subjects, aged between 1.6 and 46, median 16 years). The inborn renal tubular disorders underlying rhabdomyolysis were classic distal renal tubular acidosis (n = 7), Gitelman syndrome (n = 5), classic Bartter syndrome (n = 1), and antenatal Bartter syndrome (n = 1). In 8 patients rhabdomyolysis followed an acute intestinal disease, an upper respiratory illness or the discontinuation of regular medication. Five patients experienced two or more episodes of rhabdomyolysis. In 10 patients the underlying renal tubular disorder was recognized concurrently with the episode of rhabdomyolysis or some weeks later. In conclusion some congenital renal tubular disorders predispose to hypokalemic rhabdomyolysis. Prevention of discontinuation of regular medication and electrolyte repair in the context of acute intercurrent illnesses might avoid the development of hypokalemic rhabdomyolysis.

Mutational analysis of CLC-5, cofilin and CLC-4 in patients with Dent's disease.

BACKGROUND/AIMS: Dent's disease is caused by mutations in the chloride/proton antiporter, CLC-5, or oculo-cerebro-renal-syndrome-of-Lowe (OCRL1) genes. METHODS: Eighteen probands with Dent's disease were investigated for mutations in CLC-5 and two of its interacting proteins, CLC-4 and cofilin. Wild-type and mutant CLC-5s were assessed in kidney cells. Urinary calcium excretion following an oral calcium challenge was studied in one family. RESULTS: Seven different CLC-5 mutations consisting of two nonsense mutations (Arg347Stop and Arg718Stop), two missense mutations (Ser244Leu and Arg516Trp), one intron 3 donor splice site mutation, one deletion-insertion (nt930delTCinsA) and an in-frame deletion (523delVal) were identified in 8 patients. In the remaining 10 patients, DNA sequence abnormalities were not detected in the coding regions of CLC-4 or cofilin, and were independently excluded for OCRL1. Patients with CLC-5 mutations were phenotypically similar to those without. The donor splice site CLC-5 mutation resulted in exon 3 skipping. Electrophysiology demonstrated that the 523delVal CLC-5 mutation abolished CLC-5-mediated chloride conductance. Sixty percent of women with the CLC-5 deletion-insertion had nephrolithiasis, although calcium excretion before and after oral calcium challenge was similar to that in unaffected females. CONCLUSIONS: Three novel CLC-5 mutations were identified, and mutations in OCRL1, CLC-4 and cofilin excluded in causing Dent's disease in this patient cohort.

Patients with biallelic mutations in the chloride channel gene CLCNKB: long-term management and outcome.

BACKGROUND: Little information on the management and long-term follow-up of patients with biallelic mutations in the chloride channel gene CLCNKB is available. METHODS: Long-term follow-up was evaluated from 5.0 to 24 years (median, 14 years) after diagnosis in 13 patients with homozygous (n = 10) or compound heterozygous (n = 3) mutations. RESULTS: Medical treatment at last follow-up control included supplementation with potassium in 12 patients and sodium in 2 patients and medical treatment with indomethacin in 9 patients. At the end of follow-up, body height was 2.0 standard deviation score or less in 6 patients; 2 of these patients had growth hormone deficiency. Body weight (

Identification of fifteen novel mutations in the SLC12A3 gene encoding the Na-Cl Co-transporter in Italian patients with Gitelman syndrome.

The SLC12A3 gene encodes the thiazide-sensitive Na-Cl co-transporter (NCCT) expressed in the apical membrane of the distal convoluted tubule of the kidney. Inactivating mutations of this gene are responsible for Gitelman syndrome (GS), a disorder inherited as an autosomal recessive trait. We searched for SLC12A3 gene mutations in 21 Italian patients with the clinical and biochemical features of GS (hypokalemia, hypomagnesemia, metabolic alkalosis, hypocalciuria, and the absence of nephrocalcinosis). All coding regions with their intron-exon boundaries were analyzed using PCR and SSCP techniques followed by sequencing analysis. We identified 21 different mutations evenly distributed throughout the gene without any mutation hot-spot. Fifteen are novel variants, including 12 missense mutations, one deletion, one deletion-insertion and one splice site mutation: R158Q, T163M, W172R, G316V, G374V, G463E, A464T, S615W, V677M, R852S, R958G, C985Y, 2114-2120delACCAAGT, 2144-2158delGCCTTCTACTCGGATinsTG, and 531-2A>G.