KCNJ11 Research Articles

Potassium inwardly-rectifying channel subfamily J member 11 (KCNJ11) gene polymorphism in Egyptian type 2 diabetic patients: a single-center study.

The KCNJ11 gene belongs to the potassium channel gene family. It has a major role inthe secretion of insulin. Genetic variations in KCNJ11 are possibly responsible for the progression of type 2 diabetes mellitus (T2DM). In this study, we investigated the possible correlation between KCNJ11 (rs5210) gene polymorphism and T2DM. This study included 92 individuals divided into two groups. Group 1 included 46 type 2 diabetic patients. Group 2 (control group) included 46 healthy participants. A complete history was taken and a full physical examination was performed. Anthropometric data were measured. Laboratory investigations included fasting blood glucose (FBG), two hours post-prandial blood glucose (2HPPBG), glycated hemoglobin (HbA1c), and fasting lipid profile. KCNJ11 (rs5210) single nucleotide polymorphism was detected by polymerase chain reaction restriction-fragment length polymorphism (PCR-RFLP). Both AG and GG genotypes were associated with increased risk for T2DM (OR 5.2, 95% CI 1.32-20.5, P = 0.01 for AG; and OR 18.2, 95% CI 2.99-31.7, P = 0.002 for GG). Also, the frequency of the G allele was significantly higher in type 2 diabetic patients compared to healthy controls (50% versus 23.9%, respectively). The G allele of rs5210 in KCNJ11 contributed to an increased risk of T2DM (OR 3.18, 95% CI 1.31-7.75, P = 0.01). There was a statistically significant association between increased 2HPPBG and HbA1c levels and the carrier of AG and GG genotypes (P = 0.01 and 0.007, respectively). There was a statistically significant association between total cholesterol(TC), low-density lipoprotein-cholesterol (LDL-c), and high-density lipoprotein-cholesterol (HDL-c) levels and the carrier of AG and GG genotypes (P < 0.001, 0.02, and 0.007, respectively). Regression analysis detected that body mass index (BMI), 2HPPBG, TC, triglycerides (TG), and the G allele of rs5210 in KCNJ11 gene showed a significant association with T2DM (P = 0.004, 0.042, 0.003, 0.006, and 0.01, respectively) while no association was observed with FBG, HbA1c, LDL-c or HDL-c (P = 0.099, 0.123, 0.522, and 0.765, respectively). KCNJ11 rs5210 genetic polymorphism may raise the risk for the occurrence ofT2DM among Egyptians.

Molecular and clinical profiles of pediatric monogenic diabetes subtypes: comprehensive genetic analysis of 138 patients.

Single gene variants that give rise to neonatal diabetes mellitus (NDM), maturity onset diabetes of the young (MODY) and syndromic forms of diabetes mellitus (SDM) are responsible for 3.1-4.2% of all diabetes cases. This single-center study with a relatively larger sample size aimed to evaluate the clinical and genetic characteristics of Chinese children with suspected monogenic diabetes (MD) using next generation sequencing (NGS) methods. Data were collected from 1550 consecutive children diagnosed with diabetes/hyperglycemia at the Endocrinology Department of Children's Hospital of Nanjing Medical University from 2012 to 2023. The genotype and phenotype of 138 children with suspected MD were retrospectively analyzed. Among 138 children, 16, 97, and 25 patients with NDM, suspected MODY and SDM were assessed by NGS, with a pick-up rate of 87.5%, 57.8%, and 56%, respectively. In total, there was a high pick-up rate of MD, with 58% (80 of 138) among antibody-negative pediatric patients. Pathogenic variants were found in GCK, HNF1A, INS, KCNJ11, INSR, HNF4A, ABCC8, WFS1, ALMS1, HNF1B, BLK and ZFP57 genes with 13 novel variants in addition to 4 patients with CNVs. In this cohort, GCK-MODY was the leading cause and the mildest type of MODY. GCK-MODY displayed favorable lipid profile when compared to non-GCK-MODY and MODYX, which might be cardioprotective. Following an accurate genetic diagnosis of diabetes, 19 patients switched from insulin therapy to oral agents or lifestyle interventions. NGS tests helped to identify the precise etiology of monogenic diabetic patients which has implications for better individualized management.

Persistent renal dysfunction post-chemotherapy: a diagnostic conundrum in pediatric cancer survivorship – a case report

BackgroundLate-onset type II Bartter syndrome is an exceedingly rare condition, with only six documented cases presenting symptoms and signs beyond infancy. We report a unique case of late-onset type II Bartter syndrome with an atypical presentation and clinical course following chemotherapy treatment during childhood.Case presentationA 10-year-old boy, diagnosed with hepatoblastoma at age 2 and treated with cisplatin and epirubicin, presented with polyuria, polydipsia, failure to thrive, and electrolyte imbalances. He exhibited hypokalemia, metabolic alkalosis, and elevated urinary excretion of sodium, chloride, calcium, and magnesium. Whole exome sequencing and Sanger sequencing identified compound heterozygous variants in the KCNJ1 gene, confirming the diagnosis of type II Bartter syndrome. The patient’s clinical presentation was distinct from previously reported cases, with an absence of nephrocalcinosis, unusually small and hyperechoic kidneys, and a substantial decline in kidney function. Treatment included oral potassium supplementation, spironolactone, and angiotensin-converting enzyme inhibitors.ConclusionsThis case highlights the importance of considering late-onset Bartter syndrome in patients with a history of chemotherapy presenting with persistent electrolyte imbalances and ongoing renal dysfunction. The atypical features and rapid progression of chronic kidney disease in this patient may be attributed to the deleterious nature of the identified variants and the potential impact of previous chemotherapy on kidney susceptibility to damage. Careful monitoring and management of electrolyte imbalances and renal function are crucial in such cases.

Compound Heterozygous Loss of Allele Coding for KCNJ16 in an Adult Presenting as Recurrent Hypokalemic Periodic Paralysis with Metabolic Acidosis and Hypokalemia

A 20-year-old male presented with fever and rapidly progressive muscle weakness. He had hypokalemia and metabolic acidosis, suggesting renal tubular acidosis (RTA). Further investigation revealed distal RTA with preserved acidification. A channelopathy was suspected. Whole exome sequencing identified a novel biallelic mutation in the KCNJ16 gene, which encodes the Kir5.1 protein. This is the first reported case of an Indian adult with biallelic KCNJ16 mutations presenting as pure renal phenotype without sensory neural hearing loss or cardiac manifestation.

8294 Association between gene mutations and DNA methylation of CYP11B2 in aldosterone-producing adenoma

Abstract Disclosure: M. Kometani: None. R. Mizoguchi: None. M. Demura: None. K. Aiga: None. S. Konishi: None. D. Aono: None. S. Karashima: None. Y. Takeda: None. T. Yoneda: None. Context: Primary aldosteronism (PA) causes hypertension and cardiovascular complications. Recently, in aldosterone producing adenomas (APA), various genetic mutations have been identified. In addition, epigenetic mechanisms, such as DNA methylation, are also involved in excessive aldosterone production. Several studies have shown that aldosterone synthase (CYP11B2) is hypomethylated in APA. On the other hand, the relationship between specific genetic variants identified in APA and DNA methylation has not been fully clarified. Objective: To investigate the relationship between specific genetic mutations in APA and DNA methylation of CYP11B2. Methods: We analyzed 48 patients (female 23 cases) diagnosed with APA and treated between 2001 and 2022. First, Gene mutation analysis using next-generation sequencing was performed. KCNJ5, ATP1A1, ATP2B3, CACNA1D, and CACNA1H, which are known mutations in PA, and PRKACA, PRKA1A, GNAS, CTNNB1, and ARMC5, which are known mutations in Cushing’s syndrome, were evaluated. Next, DNA methylation analysis of the CYP11B2 promoter using pyrosequencing were performed using APA. We targeted three CpG regions near the transcription start site of CYP11B2. Results: The respective mean values for all patients were: age 52 years, systolic blood pressure 138 mmHg, diastolic blood pressure 87 mmHg, ARR 1,326, serum potassium level 3.4 mEq/L, and tumor diameter 15 mm. Genetic mutation analysis revealed KCNJ5 gene mutations in 33 of the 48 patients. Among the other cases, mutations in the CTNNB1 gene were found in three cases, mutations in the ATP1A1 gene in two cases, mutations in the CACNA1D gene in one case, and PRKACA gene mutations in one case. The remaining seven patients had no mutations in any of the analyzed genes. When DNA methylation of the promoter region of CYP11B2 was analyzed in APAs with and without mutations in KCNJ5, we found that in all three CpG regions, DNA methylation rate was significantly reduced in APAs with mutations in KCNJ5 gene (CpG1 22% vs. 30%, CpG2 42% vs. 73%, CpG3 47% vs. 75%, respectively). Conclusions: The most common genetic mutation in APA was the KCNJ5 mutation; APA with the KCNJ5 mutation had significantly lower methylation rates than CYP11B2. This suggests that genetic mutations in APA affect DNA methylation and result in hormone overproduction. Presentation: 6/3/2024

8401 Genetic Characterization of a Case of Primary Aldosteronism in an 11-Year-Old Girl carrying a Germline VUS of CACNA1H and a Somatic Mutation of CTNNB1

Abstract Disclosure: S. Parisien-La Salle: None. G. Van Vliet: None. G. Corbeil: None. M. Labrecque: None. M. Tétreault: None. I. Bourdeau: None. Introduction: Primary aldosteronism is a frequent cause of secondary hypertension in adults but is rare in children. We report the case and genetic studies of an 11 yo girl presenting with primary aldosteronism at puberty. Case presentation: An 11-year-old female patient was referred to the pediatric endocrinology clinic for hypertension (166/118). Her past medical history and family history were unremarkable. She reported polyuria, polydipsia and occasional headaches and abdominal pain. Her Tanner stage indicated that puberty was initiated (P2M2). An abdominal CT revealed a 9x10x11cm right adrenal mass with calcifications and a necrotic zone. On [1]8F-FDG PET/CT, the mass had an uptake of 2.9 SUVmax. Laboratory results revealed hypokalemia (K: 2.6 mmol/L [N: 3.5-4.5]) and elevated aldosterone (1712.8 pmol/L [N: 110-1330]) with suppressed renin (0.2 ng/ml/h [N: &amp;lt;5.3]). Her urinary aldosterone level was elevated (114 nmol/day [N: &amp;lt;67]). The rest of the biochemical adrenal panel was normal. Patient underwent a right adrenalectomy by laparotomy. The pathology report showed an adrenal tumor without capsular or vascular invasion. The only malignancy criterion was an area of necrosis and the ki-67% proliferation index was &amp;lt; 1%. Genetic investigations: After informed consent, the patient underwent germline analysis for the chimeric gene CYP11B2/CYP11B1 (Ruhr University Bochum, Germany) and a multigene panel including KCNJ5, CACNA1D, CACNA1H and CLCN2 genes (Fulgent, CA), which were both negative except for a variant of unknown significance (VUS) that was identified in CACNA1H (c.3868G&amp;gt;A, p.Val1290Ile) with a minor allele frequency of 3.291E-5 (GnomAD). Tumor DNA was extracted after adrenalectomy from fresh frozen tissues. Somatic genetic analysis of GNAS, CTNNB1, KCNJ5, ATP1A1, ATP2B3 and CACNA1D was performed using direct Sanger Sequencing (Genome Quebec Innovation Centre) and revealed a heterozygous missence pathogenic variant in the CTNNB1 gene (c.121 A&amp;gt;G p.Thr41Ala). This mutation was absent in leukocyte DNA of the patient. Immunohistochemistry of the adrenal tumor disclosed strong cytoplasmic β-catenin staining in most tumor cells (monoclonal anti-β-catenin antibody; BD Transduction Laboratories). RNA-sequencing of patient tumor RNA was performed (Research Center CHU Québec) and compared to human adrenal total RNA (Clontech, Mountain View, CA). Pathway enrichment analysis showed activation of the Wnt signaling pathway. No variant was identified in GNAQ or GNA11 genes. However, GNRHR was upregulated compared to the control sample with a log2 fold change of 3.96 (p=0.000074). Conclusion: We present a rare pediatric case of an aldosterone producing adenoma harbouring a somatic β-catenin pathogenic variant with upregulation of GNRHR. The implication of the germline CACNA1H VUS still needs to be clarified. Presentation: 6/3/2024

8721 A Case of Congenital Hyperinsulinism Manifesting as Transient Hypoglycemia During Illness Due to Mosaic Variant of Unknown Significance in ABCC8

Abstract Disclosure: E.E. Bell-Sambataro: None. L. Mamilly: None. Background: Congenital hyperinsulinism (CHI) is characterized by inappropriate secretion of insulin during periods of low blood glucose. CHI can lead to significant complications such as seizures, developmental delays and neurologic damage. CHI can be caused by multiple genetic variants. The most common genetic etiologies are loss of function mutations in the genes ABCC8 and KCNJ11 encoding the pancreatic Beta (β)-cell ATP-sensitive potassium channel causing over secretion of insulin from the β-cells. We report a challenging pediatric case with a clinical presentation of CHI in an infant with a de novo mosaic ABCC8 gene variant of unknown significance manifesting only during times of illness. Clinical Case: A male infant born at 36 weeks gestational age was transferred to a tertiary center NICU secondary to seizure activity and hypoglycemia after the 24 hours of life with glucose levels as low as 32 mg/dL. His birth weight was normal and there was not maternal history of diabetes mellitus. The hypoglycemia persisted throughout the first week of life and required a glucose infusion rate of 11 mg/kg/min, without success in obtaining a critical sample. He had multiple seizures and MRI brain showed signs of hypoglycemic encephalopathy. Subsequently, he was weaned off IV dextrose and completed a 6 hour safety fast prior to discharge. Rapid genome testing resulted in a de novo, mosaic variant of unknown significance in ABCC8 (C.3622G&amp;gt;A resulting in amino acid substitution p.Glu1208Lys). His family reported significant but transient hypoglycemia during times of illness. At the age of 11 months, he was hospitalized for significant hypoglycemia during an episode of acute gastroenteritis and was treated with dextrose-containing fluids for 36 hours. A subsequent diagnostic fasting study resulted in hypoglycemia within 5.5 hours with capillary glucose of 49 mg/dL. At the time of hypoglycemia, beta hydroxybutyrate was inappropriately low at 0.78 mm, insulin level was suppressed &amp;lt;2 mcIU/mL. Glucagon (30 mcg/Kg) was administered after the initial sample was drawn with a significant increase in glucose from 49 mg/dL to 103 mg/dL. Based on the positive glucagon response and low serum ketone, the clinical diagnosis of CHI was made and diazoxide was initiated while awaiting other results. After the second dose of diazoxide, all glucose levels remained above 80 mg/dL. He was sent home on a continuous glucose monitor and diazoxide. Conclusion: CHI can occur due to autosomal recessive or autosomal dominant ABCC8 loss-of-function mutations of which more than half are not responsive to diazoxide. In this case report, we describe the diagnosis of hyperinsulinemic hypoglycemia in an infant with an ABCC8 variant classified with unknown significance. We describe a good initial response to diazoxide in normalizing blood glucose levels in this infant. Presentation: 6/2/2024

The impact of site-specific DNA methylation in KCNJ11 promoter on type 2 diabetes

AimsThis study explores the correlation between site-specific methylation levels of the KCNJ11 promoter and type 2 diabetes mellitus (T2DM), analyzing potential molecular mechanisms. MethodsThirty patients newly diagnosed with T2DM and 30 healthy controls were selected to determine the CpG methylation levels in the promoter region of the KCNJ11 gene using the bisulfite assay. The online software JASPAR was used to predict transcription factors binding to differentially methylated sites. Key transcription factors were further validated through quantitative PCR (q-PCR) and chromatin immunoprecipitation followed by PCR (ChIP-PCR). ResultsMethylation at multiple CpG sites within the KCNJ11 gene promoter was generally reduced in newly diagnosed T2DM patients compared with healthy individuals. The methylation status of CpG-471, a site crucial for the binding of the transcription factor TCF12, emerged as potentially influential in T2DM pathogenesis. This reduction in methylation at CpG-471 may enhance TCF12 binding, thereby altering KCNJ11 expression. ConclusionHypomethylation of specific CpG sites in the promoter region of the KCNJ11 gene in patients with incipient T2DM potentially contributes to the disease's pathogenesis. This hypomethylation may influence TCF12 binding, with potential regulatory effects on KCNJ11 expression and pancreatic beta-cell function, though further studies are needed to confirm the exact mechanisms involved.

Exploring new horizons: angiotensin II, angiotensin II type 1 receptor, and renal outer medullary potassium channel interaction in distal convoluted tubule.

This study investigates angiotensin II (Ang II)'s regulatory mechanism on renal outer medullary potassium channel (ROMK) activity in the distal convoluted tubule (DCT) during low potassium intake, focusing on the Janus kinase 2 (JAK2) pathway activation mediated by the Ang II type 1 receptor (AT1R). Utilizing a low potassium diet mouse model, various methods including patch clamping, reverse transcription-quantitative polymerase chain reaction, Western blotting, and immunohistochemical staining were applied to analyze ROMK channel activity and the expression of related proteins. The findings reveal that Ang II inhibits ROMK activity in the DCT2 membrane through AT1R activation, with the JAK2 pathway playing a central role. Further, inhibiting JAK2 reverses this effect, indicating its potential in hypertension treatment. This study provides novel insights into the role of Ang II in renal potassium excretion and hypertension pathophysiology.

Clinical, myopathological, and genetic features of two Chinese families with Andersen-Tawil syndrome.

To explore the clinical, muscle pathological, and pathogenic gene mutation characteristics of Andersen-Tawil Syndrome (ATS) and enhance the understanding of ATS among clinical practitioners. Retrospective analysis of clinical data and muscle pathology of two ATS families, along with genetic testing for probands and some family members. In Family 1, spanning four generations, four individuals were affected, while Family 2 had two affected individuals across four generations. All six patients in both families experienced onset in childhood, presenting with periodic paralysis, arrhythmias, and craniofacial skeletal abnormalities. In Family 1, the proband's periodic paralysis was more triggered by low temperature and exercise, occurring several times a year, lasting 4-7 days. All three adult patients in Family 1 had a history of hypokalemia, and the frequency and severity of attacks were reduced after regular oral potassium supplement therapy. Two adult females in Family 1 experienced limb weakness triggered by stress, exertion, and premenstrual period, with milder symptoms than the proband. In Family 2, the proband's periodic paralysis typically occurred the day after excessive exertion, with a frequency of approximately 2-3 months. Two years prior, the proband developed arrhythmias without palpitations or chest tightness. The proband's brother experienced intermittent limb weakness during adolescence, remained untreated, and had sudden death at age 40. Physical examination revealed characteristic features in Family 1 and both probands: small mandible, wide eye spacing, and fifth-digit clinodactyly. Four adult patients were shorter in stature, while the growth status of a pediatric patient was indeterminate. Supplementary tests showed a history of hypokalemia during muscle weakness episodes in Family 1, while Family 2 patients had normal potassium levels during episodes. The long exercise tests were positive in both probands. Muscle MRI showed no significant abnormalities, but muscle pathology revealed rimmed vacuoles and tubular aggregates. Genetic testing identified KCNJ2 gene mutations in two probands and some of their family members, with c.407C > T (p.S136F) heterozygous mutation in Family 1 and c.652C > T (p.R218W) heterozygous mutation in Family 2. Among the clinical symptoms of the patients with Andersen-Tawil Syndrome in this study, not everyone exhibits the full triad of signs: periodic paralysis is the most common initial symptom, craniofacial and digit skeletal abnormalities are characteristic signs, and ventricular arrhythmias pose the most serious potential risk. Given that these typical symptoms were observed in 5 out of 6 patients, clinicians should pay special attention to these typical symptoms, and patients with these symptoms should be followed up over time. Muscle biopsy May reveal pathological changes such as tubular aggregates, but genetic testing for KCNJ gene mutations remains a crucial diagnostic criterion for this syndrome.

Our Experiences and Learnings in Diagnosing MODY from Non-Institutional-Based Diabetes Care Clinics

Abstract Introduction: Maturity-onset diabetes of the young (MODY) is a rare group of disorders characterised by impaired functions or development of pancreatic islets and monogenic diabetes at a young age. Diagnosing MODY can be rewarding for both clinicians and patients as it can change the management from generic to targeted therapy. Methods: This study reports the retrospective analysis of data collected from four clinics between March 2016 and February 2023 from Lucknow, a city in northern India. Fifty-three individuals are suspected to be affected by MODY based on ISPAD guidelines. Following a detailed clinical evaluation, they were referred for genetic diagnostic testing. Results: The cohort consists of 19 females and 34 males with a mean age of diagnosis of 25.3 years and a body mass index of 22.3 Kg/m2. Genetic testing detected variants in 13/53 (~24.5%) individuals. Five cases had significant pathogenic/likely pathogenic variants, HNF1A gene in two [(p.Phe268LeufsTer74) (p.Arg200Gln)], one each in HNF4A (Arg311His), PDX1(p.Ala228GlyfsTer33), and a case with suggestive digenic variants in HNF1A gene (p.Arg200Gln) and HNF1B [(p.Leu13Met)]. Variants of uncertain significance (VUSs) with inconclusive evidence of pathogenicity were reported in eight patients, and five were considered to be clinically significant as they are lean young onset, sulfonylurea-responsive, and presented with diabetes without acanthosis nigricans and with high pretest probability. These individuals harboured variants in HNF1A (p.Thr425_Thr429delinsPro), HNF1B (p.Ser19Phe), CEL (p.Val681ArgfsTer6), ABCC8 (p.Ile872Met), and KCNJ11 (p.Arg221Cys) genes. Conclusion: We found a diagnostic yield of around 10% of pathogenic or likely pathogenic variants in individuals who were suspected to have MODY. As it is a field that is still evolving, we might consider starting with oral agents under close supervision in those individuals who have VUS; there are some proportions of individuals who might not have classical sulfonylurea-responsive genetic variants, but they might respond to it.

Characterization of hyperactive mutations in the renal potassium channel ROMK uncovers unique effects on channel biogenesis and ion conductance.

Hypertension affects one billion people worldwide and is the most common risk factor for cardiovascular disease, yet a comprehensive picture of its underlying genetic factors is incomplete. Amongst regulators of blood pressure is the renal outer medullary potassium (ROMK) channel. While select ROMK mutants are prone to premature degradation and lead to disease, heterozygous carriers of some of these same alleles are protected from hypertension. Therefore, we hypothesized that gain-of-function (GoF) ROMK variants which increase potassium flux may predispose people to hypertension. To begin to test this hypothesis, we employed genetic screens and a candidate-based approach to identify six GoF variants in yeast. Subsequent functional assays in higher cells revealed two variant classes. The first group exhibited greater stability in the endoplasmic reticulum, enhanced channel assembly, and/or increased protein at the cell surface. The second group of variants resided in the PIP2-binding pocket, and computational modeling coupled with patch-clamp studies demonstrated lower free energy for channel opening and slowed current rundown, consistent with an acquired PIP2-activated state. Together, these findings advance our understanding of ROMK structure-function, suggest the existence of hyperactive ROMK alleles in humans, and establish a system to facilitate the development of ROMK-targeted antihypertensives.

Association of KCNJ11 gene (rs5219) polymorphism with HOMA-IR &amp; HOMA B values in type 2 diabetes mellitus in India: A case-control study

Objectives Type 2 diabetes mellitus (T2DM) is a complex illness that results from either insulin resistance or insufficient insulin, which raises blood sugar levels. Numerous genes interact to influence the secretion of insulin. A gene of great interest is KCNJ11 of subfamily-J, member 11, which functions as an inwardly rectifying ATP-sensitive potassium (KATP) channel in pancreatic beta cells and is involved in glucose-stimulated insulin release. Material &amp; Methods The present case-control study attempts to delineate the genetic impact of KCNJ11 (rs5219) gene polymorphism on the risk of T2DM in the Indian population. It involves 55 patients with type 2 diabetes (fasting plasma glucose of &gt;126 mg/dl, 2-h glucose of &gt;200 mg/dl, or HbA1c level of &gt;6.4%) and 55 healthy controls (fasting plasma glucose of &lt;100 mg/dl, 2-h glucose of &lt;140 mg/dl, or HbA1c level of &lt;6.4%). polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) was used to study KCNJ11 polymorphism through a standard protocol. Enzyme Linked Immunosorbent Assay (ELISA) was used to estimate serum Insulin levels. HOMA-IR &amp; HOMA-β values were calculated. Statistical analysis was done using t-test, Chi-Square test, and One-way analysis of variance (ANOVA) test. Results Serum insulin levels and HOMA-IR values were significantly decreased in cases than in the control group. Logistic regression analysis showed that the frequency of KK genotype in T2DM individuals (21.8%) was higher than the control group (9%) (p = 0.01). Frequency of K allele (38%) in patients was higher than the control group (18%) (p = 0.001). The K allele risk in diabetic patients was 9.9 times higher as compared to controls (p = 0.001, OR 9.9, 95%Cl 0.036–0.36). Homeostatic model assessment β (HOMA-β) values of KK genotype (59.9±27.8315) were lower than that of EK (76.8±33.23) and EE (127.9±44.59) genotypes (p &lt; 0.001). Conclusion The presence of KCNJ11 (rs 5219) gene polymorphism shows a noteworthy correlation with the likelihood of developing T2DM among the North Indian population. K allele is more likely to be present in individuals with T2DM than the control group. Moreover, HOMA-β values of those with the KK genotype were found to be lower than the individuals having EK and EE genotypes.

Association Study of CACNA1D, KCNJ11, KCNQ1, and CACNA1E Single-Nucleotide Polymorphisms with Type 2 Diabetes Mellitus.

Type 2 diabetes mellitus (T2DM) is a complex chronic disease characterized by decreased insulin secretion and the development of insulin resistance. Previous genome-wide association studies demonstrated that single-nucleotide polymorphisms (SNPs) present in genes coding for ion channels involved in insulin secretion increase the risk of developing this disease. We determined the association of 16 SNPs found in CACNA1D, KCNQ1, KCNJ11, and CACNA1E genes and the increased probability of developing T2DM. In this work, we performed a case-control study in 301 Mexican adults, including 201 cases with diabetes and 100 controls without diabetes. Our findings indicate a moderate association between T2DM and the C allele, and the C/C genotype of rs312480 within CACNA1D. The CAG haplotype surprisingly showed a protective effect, whereas the CAC and CGG haplotypes have a strong association with T2DM. The C allele and C/C genotype of rs5219 were significantly associated with diabetes. Also, an association was observed between diabetes and the A allele and the A/A genotype of rs3753737 and rs175338 in CACNA1E. The TGG and CGA haplotypes were also found to be significantly associated. The findings of this study indicate that the SNPs examined could serve as a potential diagnostic tool and contribute to the susceptibility of the Mexican population to this disease.

The Functional Interaction of KATP and BK Channels with Aquaporin-4 in the U87 Glioblastoma Cell.

K+ channels do play a role in cell shape changes observed during cell proliferation and apoptosis. Research suggested that the dynamics of the aggregation of Aquaporin-4 (AQP4) into AQP4-OAP isoforms can trigger cell shape changes in malignant glioma cells. Here, we investigated the relationship between AQP4 and some K+ channels in the malignant glioma U87 line. The U87 cells transfected with the human M1-AQP4 and M23-AQP4 isoforms were investigated for morphology, the gene expression of KCNJ8, KCNJ11, ABCC8, ABCC9, KCNMA1, and Cyclin genes by RT-PCR, recording the whole-cell K+ ion currents by patch-clamp experiments. AQP4 aggregation into OAPs increases the plasma membrane functional expression of the Kir6.2 and SUR2 subunits of the KATP channels and of the KCNMA1 of the BK channels in U87 cells leading to a large increase in inward and outward K+ ion currents. These changes were associated with changes in morphology, with a decrease in cell volume in the U87 cells and an increase in the ER density. These U87 cells accumulate in the mitotic and G2 cell cycle. The KATP channel blocker zoledronic acid reduced cell proliferation in both M23 AQP4-OAP and M1 AQP4-tetramer-transfected cells, leading to early and late apoptosis, respectively. The BK channel sustains the efflux of K+ ions associated with the M23 AQP4-OAP expression in the U87 cells, but it is downregulated in the M1 AQP4-tetramer cells. The KATP channels are effective in the M1 AQP4-tetramer and M23 AQP4-OAP cells. Zoledronic acid can be effective in targeting pathogenic M1 AQP4-tetramer cell phenotypes inhibiting KATP channels and inducing early apoptosis.

Kir6.1, a component of an ATP-sensitive potassium channel, regulates natural killer cell development.

Involved in immunity and reproduction, natural killer (NK) cells offer opportunities to develop new immunotherapies to treat infections and cancer or to alleviate pregnancy complications. Most current strategies use cytokines or antibodies to enhance NK-cell function, but none use ion channel modulators, which are widely used in clinical practice to treat hypertension, diabetes, epilepsy, and other conditions. Little is known about ion channels in NK cells. We show that Kcnj8, which codes for the Kir6.1 subunit of a certain type of ATP-sensitive potassium (K ATP ) channel, is highly expressed in murine splenic and uterine NK cells compared to other K + channels previously identified in NK cells. Kcnj8 expression is highest in the most mature subset of splenic NK cells (CD27 - CD11b + ) and in NKG2A + or Ly49C/I + educated uterine NK cells. Using patch clamping, we show that a subset of NK cells expresses a current sensitive to the Kir6.1 blocker PNU-37883A. Kcnj8 does not participate in NK cell degranulation in response to tumor cells in vitro or rejection of tumor cells in vivo . Transcriptomics show that genes previously implicated in NK cell development are amongst those differentially expressed in CD27 - CD11b + NK cells deficient of Kcnj8 . Indeed, we found that mice with NK-cell specific Kcnj8 gene ablation have fewer CD11b + CD27 - and KLRG-1 + NK cells in the bone barrow and spleen. These results show that the K ATP subunit Kir6.1 has a key role in NK-cell development.

Clinical value of 68Ga-pentixafor PET/CT in patients with primary aldosteronism and bilateral lesions: preliminary results of a single-centre study

BackgroundSubtype diagnosis of primary aldosteronism (PA) is used to determine treatment, and the potential utility of 68Ga-pentixafor PET/CT for investigation of PA has long been recognized. The study aimed to evaluate the clinical value of 68Ga-pentixafor PET/CT in the diagnosis and prognosis of patients with bilateral lesions identified by CT.MethodsIn total, 25 patients with PA and bilateral lesions on CT were retrospectively evaluated. All patients underwent 68Ga-Pentixafor PET/CT and adrenal vein sampling. The analysis focused on establishing the relationship between bilateral adrenal lesions SUVmax and the ratio of bilateral adrenal lesions SUVmax (CON) and clinical diagnosis, treatment outcomes, and KCNJ5 gene status.ResultsThe concordance rate between 68Ga-Pentixafor PET/CT and adrenal venous sampling was 65.2% (15/23). The lateralization results of 68Ga-pentixafor PET/CT supported the clinical decisions of 20 patients with PA, 90% of whom showed effectiveness in treatment. The SUVmax on the dominant side of the surgically treated patients was higher than that of patients treated with drugs. The SUVmax of the KCNJ5 mutant group was higher than that of the KCNJ5 wild group, and 68Ga-Pentixafor uptake was correlated with KCNJ5 gene status.Conclusions68Ga-Pentixafor PET/CT proves beneficial for patients with PA with bilateral lesions on CT. The treatment is generally effective based on the results of PET lateralization. Simultaneously, a certain relationship exists between 68Ga-Pentixafor PET/CT and KCNJ5 gene status, warranting further analysis.

Clinical and genetic characteristics of congenital hyperinsulinism in Norway: A nationwide cohort study.

Congenital hyperinsulinism (CHI) is a rare, monogenic disease characterized by excessive insulin secretion. We aimed to evaluate all probands with suspected CHI in Norway registered over the past two decades. The study included 98 probands. Clinical data were cumulated from medical records. All probands were screened for variants in the genes ABCC8 and KCNJ11. Other CHI-related genes were Sanger-sequenced as indicated by the patients' phenotype (N=75) or analyzed by next-generation sequencing employing a panel of 30 CHI-related genes (N=23). Twenty-one probands (21%) received a diagnosis other than CHI, the most common being idiopathic ketotic hypoglycemia (9%) or syndromic hyperinsulinism (4%). In the final cohort of 77 CHI probands, genetic findings were revealed in 46 (60%). ABCC8 variants were most common (N=40) and five novel variants were identified. One proband harbored both the pathogenic GCK variant p.(Ala456Val) and the ABCC8 variant p.(Gly505Cys). Although most ABCC8 variants caused immediate disease onset with severe hypoglycemia and were diazoxide-unresponsive, eight probands had a heterozygous, apparently dominant variant with milder phenotype. Two probands had pathogenic variants in GLUD1, whereas variants in HADH, HNF4A, KCNJ11, and HK1 were identified in one proband each, the latter being non-coding. Neurologic sequelae were reported in 53% of the CHI probands. Of non-surgically treated probands, 43% had spontaneous resolution. The minimum birth prevalence of CHI in Norway is 1:19,400 live births. Individuals with disease-causing ABCC8 variants dominated our cohort. Patients with known genetic etiology had earlier and more severe disease-onset than genetically unsolved patients.

Role of calcineurin in regulating renal potassium (K+) excretion: Mechanisms of calcineurin inhibitor-induced hyperkalemia.

Calcineurin, protein phosphatase 2B (PP2B) or protein phosphatase 3 (PP3), is a calcium-dependent serine/threonine protein phosphatase. Calcineurin is widely expressed in the kidney and regulates renal Na+ and K+ transport. In the thick ascending limb, calcineurin plays a role in inhibiting NKCC2 function by promoting the dephosphorylation of the cotransporter and an intracellular sorting receptor, called sorting-related-receptor-with-A-type repeats (SORLA), is involved in modulating the effect of calcineurin on NKCC2. Calcineurin also participates in regulating thiazide-sensitive NaCl-cotransporter (NCC) in the distal convoluted tubule. The mechanisms by which calcineurin regulates NCC include directly dephosphorylation of NCC, regulating Kelch-like-3/CUL3 E3 ubiquitin-ligase complex, which is responsible for WNK (with-no-lysin-kinases) ubiquitination, and inhibiting Kir4.1/Kir5.1, which determines NCC expression/activity. Finally, calcineurin is also involved in regulating ROMK (Kir1.1) channels in the cortical collecting duct and Cyp11 2 expression in adrenal zona glomerulosa. In summary, calcineurin is involved in the regulation of NKCC2, NCC, and inwardly rectifying K+ channels in the kidney, and it also plays a role in modulating aldosterone synthesis in adrenal gland, which regulates epithelial-Na+-channel expression/activity. Thus, application of calcineurin inhibitors (CNIs) is expected to abrupt calcineurin-mediated regulation of transepithelial Na+ and K+ transport in the kidney. Consequently, CNIs cause hypertension, compromise renal K+ excretion, and induce hyperkalemia.

Cross-continental environmental and genome-wide association study on children and adolescent anxiety and depression.

Anxiety and depression in children and adolescents warrant special attention as a public health concern given their devastating and long-term effects on development and mental health. Multiple factors, ranging from genetic vulnerabilities to environmental stressors, influence the risk for the disorders. This study aimed to understand how environmental factors and genomics affect children and adolescents anxiety and depression across three cohorts: Adolescent Brain and Cognitive Development Study (US, age of 9-10; N=11,875), Consortium on Vulnerability to Externalizing Disorders and Addictions (INDIA, age of 6-17; N=4,326) and IMAGEN (EUROPE, age of 14; N=1888). We performed data harmonization and identified the environmental impact on anxiety/depression using a linear mixed-effect model, recursive feature elimination regression, and the LASSO regression model. Subsequently, genome-wide association analyses with consideration of significant environmental factors were performed for all three cohorts by mega-analysis and meta-analysis, followed by functional annotations. The results showed that multiple environmental factors contributed to the risk of anxiety and depression during development, where early life stress and school support index had the most significant and consistent impact across all three cohorts. In both meta, and mega-analysis, SNP rs79878474 in chr11p15 emerged as a particularly promising candidate associated with anxiety and depression, despite not reaching genomic significance. Gene set analysis on the common genes mapped from top promising SNPs of both meta and mega analyses found significant enrichment in regions of chr11p15 and chr3q26, in the function of potassium channels and insulin secretion, in particular Kv3, Kir-6.2, SUR potassium channels encoded by the KCNC1, KCNJ11, and ABCCC8 genes respectively, in chr11p15. Tissue enrichment analysis showed significant enrichment in the small intestine, and a trend of enrichment in the cerebellum. Our findings provide evidences of consistent environmental impact from early life stress and school support index on anxiety and depression during development and also highlight the genetic association between mutations in potassium channels, which support the stress-depression connection via hypothalamic-pituitary-adrenal axis, along with the potential modulating role of potassium channels.