Novel mutations in the SLC12A3 gene causing Gitelman's syndrome in Swedes.

PURPOSE: Gitelman's syndrome (GS) is an inherited autosomal recessive disorder due to loss of function mutations in the SLC12A3 gene encoding the Na-Cl co-transporter (NCCT), the target of thiazide diuretics. The defective function of the NCCT, which normally is expressed in the apical membrane of the distal convolute tubule in the kidney, leads to mild hypotension, hypokalemia, hyperreninemic hyperaldosteronism, mild metabolic alkalosis, hypomagnesemia and hypocalciuria. Up to now, more than 100 mutations of the SLC12A3 gene have been described in GS patients. METHODS: We have collected 30 patients from Sweden with a clinical diagnosis of GS and undertaken a mutation screening by SSCP and successive sequencing of the 26 exons and intronic boundaries. Both mutations were identified in most (n = 28, 93%) and at least one mutation was identified in all patients. RESULTS: We found 22 different mutations evenly distributed throughout the gene, 11 of which have not been described previously. The new variants include 8 missense mutations (Glu68Lys, His69Asn, Argl45His, Vall53Met, Gly230Asp, Gly342Ala, Val677Leu and Gly867Ser), 1 insertion (c.834_835insG on exon 6) and 2 splice-site mutations (c.2667 + lT>G substitution in splicing donor site after exon 22, c.1569-1G>A substitution in the splicing acceptor site before exon 13). CONCLUSION: In Swedish patients with the clinical features of GS, disease-causing mutations in the SLC12A3 gene were identified in most patients. The spectrum of GS mutations is wide making full mutation screening of the SLC12A3 gene necessary to confirm the diagnosis.     

Hypokalemic metabolic alkalosis caused by surreptitious vomiting: report of four cases.

Four women, aged 22 to 40 years, presented with severe hypokalemia and metabolic alkalosis. Three had related neuromuscular symptoms. All four patients denied vomiting or diuretic ingestion, and a diagnosis of Bartter''s syndrome was entertained. A diagnosis of surreptitious vomiting was suspected from the characteristic urine electrolyte pattern: high values for sodium and potassium, and a chloride concentration of less than 5 mmol/l. Three patients excreted sodium and potassium primarily with bicarbonate and had an alkaline urine; the fourth patient excreted these cations primarily with an organic anion and had an acid urine (pH 5.5). Since self-induced vomiting may be a common method of weight reduction in young women, recognition of this characteristic urine electrolyte pattern will assist in the rapid diagnosis of hypokalemia and metabolic alkalosis of obscure cause.     

The molecular basis of renal tubular transport disorders

Sodium and water homeostasis are key to the survival of organisms. Reabsorption of sodium and water occurs throughout the tubule structure of the nephron, the basic functional unit of the kidney, by various transport mechanisms. Altered transport protein function can lead to renal tubular disorders resulting in metabolic alkalosis, hypokalemia, hypertension, and decreased capacity to concentrate urine, for instance. However, recent advances in molecular physiology, molecular genetics and expression cloning systems have aided in unraveling the molecular basis of some renal tubular disorders. This review will examine the molecular basis of Bartter's syndrome, Gitelman's syndrome, Liddle's syndrome, and autosomal nephrogenic diabetes insipidus. An understanding of the molecular basis of these disorders of the human kidney can give us a better understanding of basic renal function of lower mammals and other vertebrates.     

CT perfusion and noncontrast CT in acute ischemic stroke diagnosing--is there influence on early thrombolytic therapy outcome?

The objective of this study was to compare noncontrast computed tomography (NCCT) and computed tomography perfusion (CTP) in early diagnosis of acute ischemic stroke and to define influence of these diagnostic procedures on early outcome of thrombolytic therapy (TLTH). The study included 45 patients, 35 patients submitted to NCCT and CTP and 10 patients who underwent only NCCT, before CTP was introduced. Based on the National Institute of Health Stroke Scale (NIHSS) score we compared early outcome of patients who received TLTH after NCCT only (group 1) with the early outcome of patients who received TLTH following NCCT and CTP (group 2). Statistically significant difference was found in acute stroke diagnosing between CTP and NCCT (p = 0.002). There were no statistically significant differences in TLTH early outcome between group 1 and group 2. In conclusion, CTP should be done regulary in patients presenting with acute ischemic stroke symptoms. More research needs to be done in defining exact influence of CTP implementation on the TLTH outcome.     

Short stature as a presenting symptom of attenuated Mucopolysaccharidosis type I: case report and clinical insights

Background

Mucopolysaccharidosis type I (MPS I) results in significant disease burden and early treatment is important for optimal outcomes. Recognition of short stature and growth failure as symptoms of MPS I among pediatric endocrinologists may lead to earlier diagnosis and treatment.

Case presentation

A male patient first began experiencing hip pain at 5 years of age and was referred to an endocrinologist for short stature at age 7. Clinical history included recurrent respiratory infections, sleep apnea, moderate joint contractures, mild facial dysmorphic features, scoliosis, and umbilical hernia. Height was more than ??2 SD below the median at all time points. Growth velocity was below the 3rd percentile. Treatment for short stature included leuprolide acetate and recombinant human growth hormone. The patient was diagnosed with MPS I and began enzyme replacement therapy with laronidase at age 18.

Conclusions

The case study patient had many symptoms of MPS I yet remained undiagnosed for 11 years after presenting with short stature. The appropriate path to MPS I diagnosis when patients present with short stature and/or growth failure plus one or more of the common signs of attenuated disease is described. Improved awareness regarding association of short stature and growth failure with attenuated MPS I is needed since early identification and treatment significantly decreases disease burden.

     

Cocaine: its use in otolaryngology

A review of 120 patients who had a discharge diagnosis of intermediate coronary syndrome showed 12 patients with documented transient ST elevation during spontaneous rest pain consistent with Prinzmetal''s angina. Coronary arteriography showed severe proximal occlusive coronary atherosclerosis in nine of the patients, and normal or minimal disease in the other three patients. In two of these three, there was documented coronary arterial spasm with reproduction of symptoms during arteriography. Although a shorter history of chest pain, presence of an old myocardial infarction and a positive finding on electrocardiogram treadmill test tended to predict the patients with severe occlusive coronary artery disease, these methods were inadequate to select candidates for arteriography. All patients responded well to nitroglycerine while in the hospital. Five of the nine patients with coronary artery disease had coronary bypass operations, with two excellent, two fair and one poor result. One of the three patients with normal findings on coronary arteriograms died with refractory ventricular arrhythmia six months after study. The other two have had good-to-moderate relief of symptoms on long-acting vasodilators and propranolol. Current concepts of the syndrome of Prinzmetal''s angina and ST elevation are reviewed. It appears that this syndrome has a wide spectrum of clinical presentations and coronary arteriographic anatomies.     

Novel molecular variants of the Na-Cl cotransporter gene are responsible for Gitelman syndrome.

A hereditary defect of the distal tubule accounts for the clinical features of Gitelman syndrome (GS), an autosomal recessive disease characterized by hypokalemia, hypomagnesemia, metabolic alkalosis, and hypocalciuria. Recently, we cloned the cDNA coding for the human Na-Cl thiazide-sensitive cotransporter (TSC; also known as ¿NCCT¿ or ¿SLC12A3¿) as a possible candidate for GS, and Simon et al., independently, described mutations in patients with GS. Now, we show 12 additional mutations consistent with a loss of function of the Na-Cl cotransporter in GS. Two missense replacements, R209W and P349L, are common to both studies and could represent ancient mutations. The other mutations include three deletions, two insertions, and six missense mutations. When all mutations from both studies are considered, missense mutations seem to be more frequently localized within the intracellular domains of the molecule, rather than in transmembrane or extracellular domains. One family, previously reported as a GS form with dominant inheritance, has proved to be recessive, with the affected child being a compound heterozygote. A highly informative intragenic tetranucleotide marker, useful for molecular diagnostic studies, has been identified at the acceptor splice site of exon 9.     

Hypokalemia and alkalosis in adipsic hypernatremia are not associated with hyperaldosteronism

Idiopathic adipsic hypernatremia (AH) is a rare disorder associated with hypokalemia and alkalosis. Hypokalemic alkalosis has been presumed to be secondary to hyperaldosteronism. We evaluated plasma renin activity, serum aldosterone, serum and urine electrolytes in a 17-year-old patient with AH on several occasions. Despite evidence of mild dehydration, serum Na >160 and K <3.2, aldosterone levels were suppressed and plasma renin activity was not elevated. Urine Na and K were not conserved. We also examined electrolyte and hormone levels in previously reported cases of AH. Aldosterone levels were not increased in any of the cases when measured. Renin secretion was increased in 2 patients. Among the compiled cases serum K was inversely correlated with serum Na (r = -0.73, p < 0.002, n = 15). Hypokalemia and alkalosis occurring in AH are not associated with secondary hyperaldosteronism. Patients with AH may have chronic renal losses of potassium leading to hypokalemia and alkalosis.     

Diabetic Ketoacidosis—A Review of Cases at a University Medical Center

Twenty-five cases of diabetic ketoacidosis were studied retrospectively with respect to clinical characteristics and results of therapy. In this series (as with all 88 patients admitted in the last five years with a diagnosis of diabetic ketoacidosis) there were no deaths. Infection was found to be the most common precipitating event, documented by physical findings and cultures in one-third of these cases.In about two-thirds of the cases, electrocardiograms which were read as abnormal on admission reverted to normal after therapy.In all patients serum potassium levels decreased from admission values; one patient became symptomatically hypokalemic.Low serum potassium levels on admission and early vigorous bicarbonate therapy are emphasized as major predisposing factors of symptomatic hypokalemia. None of the patients had overt hyperosmolar coma, lactic acidosis or cerebral edema during therapy.     

Partial Turner's syndrome in four girls with Xq duplication and Xp deficiency

Summary Four girls with some clinical symptoms of Turner's syndrome had Xq duplication and Xp deficiency, their karyotypes being 46,X,dup(X)(p113;q11), 46,X,dup(X)(p212;q211), 46,X,dup(X)(p225;q13), and 46,X,dup(X)(p222;q213). No mosaicism was found.The major clinical findings, short stature, lack of pterygium colli, and no continuous gamete production, are compared with those in three previously published cases.     

Yersinia enterocolitica arthritis in southern Sweden: a four-year follow-up study.

Thirty-eight cases of suspected yersinia arthritis occurring in southern Sweden in 1975-6 were reviewed four to five years later. In 31 cases the diagnosis was confirmed. At follow-up three of the patients had definite ankylosing spondylitis, three radiologically confirmed sacroiliitis, three extensor tenosynovitis, five isolated articular joint disease, and 10 localised arthralgias; one patient had developed seropositive rheumatoid arthritis. Only six of the 31 patients were free of joint symptoms. These results suggest that although the acute symptoms of yersinia arthritis disappear within 12 months, the long-term prognosis may be less favourable than previously thought.     

Fecal and salivary electrolytes in the diagnosis of primary aldosteronism

Fecal and salivary sodium and potassium concentrations were measured in 22 hypertensive patients with hypokalemia who were undergoing investigation for primary aldosteronism due to an adrenocortical adenoma (Conn''s syndrome). Of eight patients with a high aldosterone secretion rate, five had clearly low fecal Na/K ratios, (including all four patients with Conn''s syndrome), in three the ratios were equivocal. Of 14 patients with hypertension and a normal aldosterone secretion rate, none had a sufficiently low fecal Na/K ratio strongly to suggest hyperaldosteronism, although two were borderline. Salivary electrolyte concentrations were not as consistent an indicator of mineralocorticoid hormone excess. Estimation of fecal sodium and potassium concentrations may be useful in the diagnosis of mineralocorticoid hormone excess and in assessing the results of therapy.     

A mutation screen in patients with Kabuki syndrome

Kabuki syndrome (KS) is one of the classical, clinically well-known multiple anomalies/mental retardation syndromes, mainly characterized by a very distinctive facial appearance in combination with additional clinical signs such as developmental delay, short stature, persistent fingerpads, and urogenital tract anomalies. In our study, we sequenced all 54 coding exons of the recently identified MLL2 gene in 34 patients with Kabuki syndrome. We identified 18 distinct mutations in 19 patients, 11 of 12 tested de novo. Mutations were located all over the gene and included three nonsense mutations, two splice-site mutations, six small deletions or insertions, and seven missense mutations. We compared frequencies of clinical symptoms in MLL2 mutation carriers versus non-carriers. MLL2 mutation carriers significantly more often presented with short stature and renal anomalies (p?=?0.026 and 0.031, respectively), and in addition, MLL2 carriers obviously showed more frequently a typical facial gestalt (17/19) compared with non-carriers (9/15), although this result was not statistically significant (p?=?0.1). Mutation-negative patients were subsequently tested for mutations in ten functional candidate genes (e.g. MLL, ASC2, ASH2L, and WDR5), but no convincing causative mutations could be found. Our results indicate that MLL2 is the major gene for Kabuki syndrome with a wide spectrum of de novo mutations and strongly suggest further genetic heterogeneity.     

Brown-Vialetto-Van Laere syndrome

Monosomy 18p refers to a chromosomal disorder resulting from the deletion of all or part of the short arm of chromosome 18. The incidence is estimated to be about 1:50,000 live-born infants. In the commonest form of the disorder, the dysmorphic syndrome is very moderate and non-specific. The main clinical features are short stature, round face with short philtrum, palpebral ptosis and large ears with detached pinnae. Intellectual deficiency is mild to moderate. A small subset of patients, about 10–15 percent of cases, present with severe brain/facial malformations evocative of holoprosencephaly spectrum disorders. In two-thirds of the cases, the 18p- syndrome is due to a mere terminal deletion occurring de novo, in one-third the following are possible: a de novo translocation with loss of 18p, malsegregation of a parental translocation or inversion, or a ring chr18. Parental transmission of the 18p- syndrome has been reported. Cytogenetic analysis is necessary to make a definite diagnosis. Recurrence risk for siblings is low in de novo deletions and translocations, but is significant if a parental rearrangement is present. Deletion 18p can be detected prenatally by amniocentesis or chorionic villus sampling and cytogenetic testing. Differential diagnosis may include a wide number of syndromes with short stature and mild intellectual deficiency. In young children, deletion 18p syndrome may be vaguely evocative of either Turner syndrome or trisomy 21. No specific treatment exists but speech therapy and early educational programs may help to improve the performances of the children. Except for the patients with severe brain malformations, the life expectancy does not seem significantly reduced.     

Gene mutations and clinical phenotypes in Chinese children with Blau syndrome

The mutations of CARD15 gene and clinical features of Chinese patients with Blau syndrome were analyzed. We identified10 missense mutations, out of which five were new: R334 L, E383 D, R471 C, C495 R and D512 F. The rest of them, R334 W,R334Q, G481 D, M513 T and R587 C, have been reported previously. Among all the mutations, R334 W, R334 Q and C495 R had the highest frequency. Blau syndrome was found at early age after birth. It began with lepidic rash and symmetric polyarthritis and was phenotypically characterized by typical rash, arthritis, iridocyclitis and arteritis. Cardiac involvement was also found in Blau syndrome. In addition to nerve deafness, renal involvement, osteochondroma and central nervous system involvement were also found in our patients. Therefore, Chinese children with Blau syndrome have unique gene mutations and complicated clinical phenotypes. Pathologic examination and CARD15 mutation testing should be considered for diagnosis as early as possible for suspected patients.     

Congenital joint dislocations caused by carbohydrate sulfotransferase 3 deficiency in recessive Larsen syndrome and humero-spinal dysostosis

Deficiency of carbohydrate sulfotransferase 3 (CHST3; also known as chondroitin-6-sulfotransferase) has been reported in a single kindred so far and in association with a phenotype of severe chondrodysplasia with progressive spinal involvement. We report eight CHST3 mutations in six unrelated individuals who presented at birth with congenital joint dislocations. These patients had been given a diagnosis of either Larsen syndrome (three individuals) or humero-spinal dysostosis (three individuals), and their clinical features included congenital dislocation of the knees, elbow joint dysplasia with subluxation and limited extension, hip dysplasia or dislocation, clubfoot, short stature, and kyphoscoliosis developing in late childhood. Analysis of chondroitin sulfate proteoglycans in dermal fibroblasts showed markedly decreased 6-O-sulfation but enhanced 4-O-sulfation, confirming functional impairment of CHST3 and distinguishing them from diastrophic dysplasia sulphate transporter (DTDST)-deficient cells. These observations provide a molecular basis for recessive Larsen syndrome and indicate that recessive Larsen syndrome, humero-spinal dysostosis, and spondyloepiphyseal dysplasia Omani type form a phenotypic spectrum.     

Increased percentage of CD8+CD28- T cells correlates with clinical activity in primary Sjögren's syndrome

The role of CD28- T cell subpopulations in primary Sj?gren's syndrome (pSS) has become controversial. Changes in the number of CD28- T cells have been demonstrated in autoimmune diseases in co-existence with Sj?gren's syndrome. The study aimed to indicate differences in the number of CD4+CD28- and CD8+CD28- T cells in patients with sicca syndrome and suspected pSS. Thirty patients with sicca syndrome at baseline were studied and followed up for 5months. After final diagnosis, comparison was made of the previously recorded lymphocyte subpopulations in patients with pSS and those in other defined subgroups. Notably high percentages of CD8+CD28- T cells were indicated in pSS patients, which correlated with the severity of the sicca symptoms and cutaneous and muscular systemic disease activity. Changes in CD8+CD28- T cell percentages may thus assist in the early differential diagnosis of pSS patients from those with similar clinical symptoms.     

Genetic analysis of tall stature

Tall stature is less often experienced as an important problem than short stature. However, a correct diagnosis may be of eminent importance, especially when interventions are planned, or to know the natural history. Overgrowth can be caused by endocrine disorders and skeletal dysplasias, but also by several genetic syndromes. Despite a systematic diagnostic approach, there will be patients with tall stature who do not fit a known diagnosis. In this group of patients possibilities of genetic analysis do exist, but are not common practice. The FMR1 gene should be analyzed in patients with tall stature and mental retardation, and in these patients the NSD1 gene can be considered whenever some features of Sotos syndrome do exist. In tall patients without mental retardation and some features of Sotos or Beckwith-Wiedemann syndrome it may still be useful to look for mutations in the NSD1 gene, but also for changes in the 11p15 region. The various possibilities are discussed and placed in a flowchart.     

Treatment with 17-allylamino-17-demethoxygeldanamycin ameliorated symptoms of Bartter syndrome type IV caused by mutated Bsnd in mice

Mutations of BSND, which encodes barttin, cause Bartter syndrome type IV. This disease is characterized by salt and fluid loss, hypokalemia, metabolic alkalosis, and sensorineural hearing impairment. Barttin is the β-subunit of the ClC-K chloride channel, which recruits it to the plasma membranes, and the ClC-K/barttin complex contributes to transepithelial chloride transport in the kidney and inner ear. The retention of mutant forms of barttin in the endoplasmic reticulum (ER) is etiologically linked to Bartter syndrome type IV. Here, we report that treatment with 17-allylamino-17-demethoxygeldanamycin (17-AAG), an Hsp90 inhibitor, enhanced the plasma membrane expression of mutant barttins (R8L and G47R) in Madin–Darby canine kidney cells. Administration of 17-AAG to Bsnd^R8L/R8L knock-in mice elevated the plasma membrane expression of R8L in the kidney and inner ear, thereby mitigating hypokalemia, metabolic alkalosis, and hearing loss. These results suggest that drugs that rescue ER-retained mutant barttin may be useful for treating patients with Bartter syndrome type IV.     

Prader-Willi syndrome: genetic tests and clinical findings

Here we describe the genetic studies performed in 53 patients with the suspected diagnosis of Prader-Willi syndrome (PWS). PWS is characterized by neonatal hypotonia, hypogonadism, delayed psychomotor development, hyperphagia, obesity, short stature, small hands and feet, learning disabilities, and obsessive-compulsive behavior. Through the methylation analysis of the SNRPN gene, microsatellite studies of loci mapped within and outside the PWS/AS region, and fluorescence in situ hybridization (FISH) study, we confirmed the diagnosis in 35 patients: 27 with a paternal deletion, and 8 with maternal uniparental disomy (UPD). The clinical comparisons between deleted and UPD patients indicated that there were no major phenotype differences, except for a lower birth length observed in the UPD children. Our sample was composed of more girls than boys; UPD patients were diagnosed earlier than the deleted cohort (2(10/12) s. 7(9/12) years); and, in the deleted group, the boys were diagnosed earlier than the girls (5(2/12) vs. 7(8/12) years, respectively).