Faculty Opinions recommendation of Defects in KCNJ16 Cause a Novel Tubulopathy with Hypokalemia, Salt Wasting, Disturbed Acid-Base Homeostasis, and Sensorineural Deafness.

2021 ◽  
Author(s):  
Aylin Rodan
Keyword(s):  
Sensorineural Deafness ◽  
Acid Base ◽  
Salt Wasting

scholarly journals Defects in KCNJ16 Cause a Novel Tubulopathy with Hypokalemia, Salt Wasting, Disturbed Acid-Base Homeostasis, and Sensorineural Deafness

2021 ◽  
pp. ASN.2020111587
Author(s):  
Karl P. Schlingmann ◽  
Aparna Renigunta ◽  
Ewout J. Hoorn ◽  
Anna-Lena Forst ◽  
Vijay Renigunta ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Genetic Defect ◽  
Sensorineural Deafness ◽  
Transport Systems ◽  
Candidate Gene Approach ◽  
Disease Phenotype ◽  
Acid Base ◽  
Salt Wasting ◽  
Renal Salt Wasting ◽  
Hypokalemic Alkalosis

BackgroundThe transepithelial transport of electrolytes, solutes, and water in the kidney is a well-orchestrated process involving numerous membrane transport systems. Basolateral potassium channels in tubular cells not only mediate potassium recycling for proper Na+,K+-ATPase function but are also involved in potassium and pH sensing. Genetic defects in KCNJ10 cause EAST/SeSAME syndrome, characterized by renal salt wasting with hypokalemic alkalosis associated with epilepsy, ataxia, and sensorineural deafness.MethodsA candidate gene approach and whole-exome sequencing determined the underlying genetic defect in eight patients with a novel disease phenotype comprising a hypokalemic tubulopathy with renal salt wasting, disturbed acid-base homeostasis, and sensorineural deafness. Electrophysiologic studies and surface expression experiments investigated the functional consequences of newly identified gene variants.ResultsWe identified mutations in the KCNJ16 gene encoding KCNJ16, which along with KCNJ15 and KCNJ10, constitutes the major basolateral potassium channel of the proximal and distal tubules, respectively. Coexpression of mutant KCNJ16 together with KCNJ15 or KCNJ10 in Xenopus oocytes significantly reduced currents.ConclusionsBiallelic variants in KCNJ16 were identified in patients with a novel disease phenotype comprising a variable proximal and distal tubulopathy associated with deafness. Variants affect the function of heteromeric potassium channels, disturbing proximal tubular bicarbonate handling as well as distal tubular salt reabsorption.

scholarly journals 5-Azacytidine and renal tubular dysfunction

Blood ◽  
1981 ◽  
Vol 57 (1) ◽  
pp. 182-185 ◽  
Author(s):  
BA Peterson ◽  
AJ Collins ◽  
NJ Vogelzang ◽  
CD Bloomfield
Keyword(s):  
Renal Toxicity ◽  
Tubular Damage ◽  
Tubular Dysfunction ◽  
Renal Tubular Dysfunction ◽  
Normal Range ◽  
Acid Base ◽  
Salt Wasting ◽  
Renal Tubular ◽  
Renal Abnormalities ◽  
Electrolyte Abnormalities

Abstract During initial trials of 5-azacytidine in adults with advanced acute leukemia, we unexpectedly observed acid-base, fluid, and electrolyte abnormalities that contributed directly to the deaths of two early patients. To evaluate this toxicity further, we studied 22 patients who received a total of 33 courses of combination chemotherapy that included 5-azacytidine. During 29 courses (88%) of treatment, polyuria, glucosuria, and/or transient changes in the serum concentrations of bicarbonate or phosphorus were detected. Spontaneous polyuria with demonstrable salt wasting and orthostatic hypotension occurred during seven courses (21%) of treatment. Inappropriate glucosuria was observed in nine courses (27%). In 24 courses (73%) the serum bicarbonate fell below the normal range. The urine became alkaline during 12 of these instances; the anion gap was not increased during the acidosis. Hypophosphatemia with serum phosphorus concentrations as low as 0.3 mg/dl occurred in 21 of 32 evaluable courses (66%). In the three patients studied the tubular reabsorption of phosphorus was 10%-18%. The renal abnormalities that were observed suggest both proximal and distal tubular damage from 5-azacytidine. Patients receiving 5- azacytidine should be monitored closely for manifestations of renal toxicity.

scholarly journals Acidosis and Deafness in Patients with Recessive Mutations in FOXI1

2017 ◽  
Vol 29 (3) ◽  
pp. 1041-1048 ◽  
Author(s):  
Sven Enerbäck ◽  
Daniel Nilsson ◽  
Noel Edwards ◽  
Mikael Heglind ◽  
Sumaya Alkanderi ◽  
...  
Keyword(s):  
Dna Binding ◽  
Inner Ear ◽  
Renal Tubular Acidosis ◽  
Cultured Cells ◽  
Collecting Duct ◽  
Sensorineural Deafness ◽  
Distal Renal Tubular Acidosis ◽  
Acid Base ◽  
Recessive Mutations ◽  
Renal Tubular

Maintenance of the composition of inner ear fluid and regulation of electrolytes and acid-base homeostasis in the collecting duct system of the kidney require an overlapping set of membrane transport proteins regulated by the forkhead transcription factor FOXI1. In two unrelated consanguineous families, we identified three patients with novel homozygous missense mutations in FOXI1 (p.L146F and p.R213P) predicted to affect the highly conserved DNA binding domain. Patients presented with early-onset sensorineural deafness and distal renal tubular acidosis. In cultured cells, the mutations reduced the DNA binding affinity of FOXI1, which hence, failed to adequately activate genes crucial for normal inner ear function and acid-base regulation in the kidney. A substantial proportion of patients with a clinical diagnosis of inherited distal renal tubular acidosis has no identified causative mutations in currently known disease genes. Our data suggest that recessive mutations in FOXI1 can explain the disease in a subset of these patients.

scholarly journals Life-threatening metabolic alkalosis in Pendred syndrome

2011 ◽  
Vol 165 (1) ◽  
pp. 167-170 ◽  
Author(s):  
Narayanan Kandasamy ◽  
Laura Fugazzola ◽  
Mark Evans ◽  
Krishna Chatterjee ◽  
Fiona Karet
Keyword(s):  
Metabolic Alkalosis ◽  
Collecting Duct ◽  
Sensorineural Deafness ◽  
Apical Plasma Membrane ◽  
Cortical Collecting Duct ◽  
Loss Of Function ◽  
Pendred Syndrome ◽  
Acid Base ◽  
Life Threatening ◽  
Acid Base Status

IntroductionPendred syndrome, a combination of sensorineural deafness, impaired organification of iodide in the thyroid and goitre, results from biallelic defects in pendrin (encoded by SLC26A4), which transports chloride and iodide in the inner ear and thyroid respectively. Recently, pendrin has also been identified in the kidneys, where it is found in the apical plasma membrane of non-α-type intercalated cells of the cortical collecting duct. Here, it functions as a chloride–bicarbonate exchanger, capable of secreting bicarbonate into the urine. Despite this function, patients with Pendred syndrome have not been reported to develop any significant acid–base disturbances, except a single previous reported case of metabolic alkalosis in the context of Pendred syndrome in a child started on a diuretic.Case reportWe describe a 46-year-old female with sensorineural deafness and hypothyroidism, who presented with severe hypokalaemic metabolic alkalosis during inter-current illnesses on two occasions, and who was found to be homozygous for a loss-of-function mutation (V138F) in SLC26A4. Her acid–base status and electrolytes were unremarkable when she was well.ConclusionThis case illustrates that, although pendrin is not usually required to maintain acid–base homeostasis under ambient condition, loss of renal bicarbonate excretion by pendrin during a metabolic alkalotic challenge may contribute to life-threatening acid–base disturbances in patients with Pendred syndrome.

Renal salt wasting in mice lacking NHE3 Na+/H+ exchanger but not in mice lacking NHE2

2001 ◽  
Vol 281 (4) ◽  
pp. F718-F727 ◽  
Author(s):  
Clara Ledoussal ◽  
John N. Lorenz ◽  
Michelle L. Nieman ◽  
Manoocher Soleimani ◽  
Patrick J. Schultheis ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Renal Function ◽  
Hypovolemic Shock ◽  
Fractional Excretion ◽  
Fluid Volume ◽  
Restricted Diet ◽  
Metabolic Disturbances ◽  
Acid Base ◽  
Salt Wasting ◽  
Renal Salt Wasting

To study the role of Na+/H+ exchanger isoform 2 (NHE2) and isoform 3 (NHE3) in sodium-fluid volume homeostasis and renal Na+ conservation, mice with Nhe2( Nhe2 −/−) and/or Nhe3( Nhe3 −/−) null mutations were fed a Na+-restricted diet, and urinary Na+ excretion, blood pressure, systemic acid-base and electrolyte status, and renal function were analyzed. Na+-restricted Nhe2 −/− mice, on either a wild-type or Nhe3 heterozygous mutant ( Nhe3 +/−) background, did not exhibit excess urinary Na+ excretion. After 15 days of Na+ restriction, blood pressure, fractional excretion of Na+, and the glomerular filtration rate (GFR) of Nhe2 −/− Nhe3 +/− mice were similar to those of Nhe2 +/+ and Nhe3 +/− mice, and no metabolic disturbances were observed. Nhe3 −/− mice maintained on a Na+-restricted diet for 3 days exhibited hyperkalemia, urinary salt wasting, acidosis, sharply reduced blood pressure and GFR, and evidence of hypovolemic shock. These results negate the hypothesis that NHE2 plays an important renal function in sodium-fluid volume homeostasis; however, they demonstrate that NHE3 is critical for systemic electrolyte, acid-base, and fluid volume homeostasis during dietary Na+ restriction and that its absence leads to renal salt wasting.

scholarly journals 5-Azacytidine and renal tubular dysfunction

Blood ◽  
1981 ◽  
Vol 57 (1) ◽  
pp. 182-185
Author(s):  
BA Peterson ◽  
AJ Collins ◽  
NJ Vogelzang ◽  
CD Bloomfield
Keyword(s):  
Renal Toxicity ◽  
Tubular Damage ◽  
Tubular Dysfunction ◽  
Renal Tubular Dysfunction ◽  
Normal Range ◽  
Acid Base ◽  
Salt Wasting ◽  
Renal Tubular ◽  
Renal Abnormalities ◽  
Electrolyte Abnormalities

During initial trials of 5-azacytidine in adults with advanced acute leukemia, we unexpectedly observed acid-base, fluid, and electrolyte abnormalities that contributed directly to the deaths of two early patients. To evaluate this toxicity further, we studied 22 patients who received a total of 33 courses of combination chemotherapy that included 5-azacytidine. During 29 courses (88%) of treatment, polyuria, glucosuria, and/or transient changes in the serum concentrations of bicarbonate or phosphorus were detected. Spontaneous polyuria with demonstrable salt wasting and orthostatic hypotension occurred during seven courses (21%) of treatment. Inappropriate glucosuria was observed in nine courses (27%). In 24 courses (73%) the serum bicarbonate fell below the normal range. The urine became alkaline during 12 of these instances; the anion gap was not increased during the acidosis. Hypophosphatemia with serum phosphorus concentrations as low as 0.3 mg/dl occurred in 21 of 32 evaluable courses (66%). In the three patients studied the tubular reabsorption of phosphorus was 10%-18%. The renal abnormalities that were observed suggest both proximal and distal tubular damage from 5-azacytidine. Patients receiving 5- azacytidine should be monitored closely for manifestations of renal toxicity.

Higher Dietary Acidity is Associated with Lower Bone Mineral Density in Postmenopausal Iranian Women, Independent of Dietary Calcium Intake

2014 ◽  
Vol 84 (3-4) ◽  
pp. 0206-0217 ◽  
Author(s):  
Seyedeh-Elaheh Shariati-Bafghi ◽  
Elaheh Nosrat-Mirshekarlou ◽  
Mohsen Karamati ◽  
Bahram Rashidkhani
Keyword(s):  
Calcium Intake ◽  
Dietary Calcium ◽  
Dietary Calcium Intake ◽  
Dietary Intakes ◽  
Iranian Women ◽  
Acid Base Balance ◽  
Mineral Density ◽  
Acid Base ◽  
Base Balance ◽  
Dietary Acid

Findings of studies on the link between dietary acid-base balance and bone mass are relatively mixed. We examined the association between dietary acid-base balance and bone mineral density (BMD) in a sample of Iranian women, hypothesizing that a higher dietary acidity would be inversely associated with BMD, even when dietary calcium intake is adequate. In this cross-sectional study, lumbar spine and femoral neck BMDs of 151 postmenopausal women aged 50 - 85 years were measured using dual-energy x-ray absorptiometry. Dietary intakes were assessed using a validated food frequency questionnaire. Renal net acid excretion (RNAE), an estimate of acid-base balance, was then calculated indirectly from the diet using the formulae of Remer (based on dietary intakes of protein, phosphorus, potassium, and magnesium; RNAERemer) and Frassetto (based on dietary intakes of protein and potassium; RNAEFrassetto), and was energy adjusted by the residual method. After adjusting for potential confounders, multivariable adjusted means of the lumbar spine BMD of women in the highest tertiles of RNAERemer and RNAEFrassetto were significantly lower than those in the lowest tertiles (for RNAERemer: mean difference -0.084 g/cm2; P=0.007 and for RNAEFrassetto: mean difference - 0.088 g/cm2; P=0.004). Similar results were observed in a subgroup analysis of subjects with dietary calcium intake of >800 mg/day. In conclusion, a higher RNAE (i. e. more dietary acidity), which is associated with greater intake of acid-generating foods and lower intake of alkali-generating foods, may be involved in deteriorating the bone health of postmenopausal Iranian women, even in the context of adequate dietary calcium intake.

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