KCNJ11 Research Articles

Focal Congenital Hyperinsulinism (CHI) Due To Paternally Inherited Variant in ABCC8 Gene: Importance of Genetic Testing & PET Imaging in Stratification & Management of Diazoxide Unresponsive CHI

Congenital Hyperinsulinism (CHI) may be transient or permanent and inherited either in autosomal recessive or dominant forms. Variants in ABCC8 and KCNJ11 genes coding for Sulphonyl Urea Receptor (SUR1) and potassium channel subunit (Kir6.2) respectively, account for 82% cases of diazoxide-unresponsive patients and 45% of all cases of CHI. The histology of CHI is classified into focal and diffuse. Approximately half of all cases can be classified as diffuse, 40 % as focal, and 10% of cases are considered atypical. We report a 1 month old male with recurrent hypoglycemia detected with focal congenital hyperinsulinism secondary to a paternally inherited heterozygous ABCC8 gene mutation. Focal disease results due to inheritance of a monoallelic recessive paternal ABCC8 or KCNJ11 variant together with somatic Loss of Heterozygosity (LOH) of the maternal allele at 11p15 within a pancreatic progenitor cell. Infants & children with focal disease may be cured by resection of their hyperplastic lesion and the risk for postoperative diabetes is significantly lower as compared to that following pancreatectomy for diffuse CHI. The report describes molecular mechanisms underlying CHI & emphasises the need of genetic testing and diagnostic functional imaging modalities in diazoxide unresponsive CHI to guide management and improve clinical outcomes.

Bidirectional Ventricular Tachycardia and Prominent U Waves: Look at Fingers and Muscles and Use Flecainide.

We present a case of bidirectional ventricular tachycardia in a 15-year-old boy asymptomatic for arrhythmias, whose major complaint was muscle weakness. At our first evaluation he was receiving sotalol for his ventricular arrhythmias. In addition to bidirectional tachycardia, electrocardiogram during sinus rhythm showed prominent U waves and prolonged QT-U interval. These electrocardiographic signs, along with the evidence of clinodactyly and mild hypertelorism, led us to the diagnosis of Andersen-Tawil syndrome, confirmed by genetic analysis that revealed a "de novo" missense mutation of KCNJ2 gene. Monotherapy with flecainide was rapidly effective and almost eliminated ventricular arrhythmias. After a 4-year follow-up there were no adverse events, flecainide has been well tolerated without significant modification of the QRS or repolarization, and ventricular arrhythmias have not been relapsed to date. The case highlights the importance of a correct clinical diagnosis, which is crucial for the optimal selection of the most appropriate drug therapy, which is expected not to be harmful, before being beneficial.

Neonatal Diabetes mellitus: A review

Neonatal diabetes mellitus is regarded as genetic, diversified, and infrequent disorder of babies. This is developed due to mutation of specific gene. ABCC8 and KCNJ11 genes mutation are fundamental cause for the development of this. These genes encrypting the potassium network and are very much involved for seeking the monogenic diabetes like Neonatal diabetes mellitus. Neonate diabetes is classified as transient diabetes mellitus and permanent diabetes mellitus. Transient diabetes mellitus is observed at infancy stage where as Permanent diabetes mellitus is observed at 7 weeks to 26 weeks. With the help of genetic screening, this classified diabetes is discriminated. Transient diabetes is observed during infant stage and furtherly starts in later life. 22 genetic variations are very much interconnected with this type of diabetes. This article will provide a summary of current knowledge on neonatal diabetes mellitus.

Levetiracetam ameliorates epileptogenesis by modulating the adenosinergic pathway in a kindling model of epilepsy in mice.

Levetiracetam (LEV) has been found to have an antihyperalgesic effect via acting on the adenosine system. However, the effects of LEV on the modulation of the adenosine system in the brain have not been elucidated in the prevention of seizures and epilepsy. The present study aimed to explore the possible LEV mechanisms of action in the adenosine signaling systems in an animal model of epilepsy. A docking study was initially performed to determine the possible interaction of LEV with adenosine A1 receptors (A1Rs) and equilibrative nucleoside transporters-1 (ENT1). The experimental study was divided into an acute seizure test (32 mice distributed into 4 groups) and a chronic kindling model study (40 mice distributed into 5 groups), followed by gene expression analysis and immunohistochemistry. The kindling model lasted 26 days and took 13 subconvulsive doses of pentylenetetrazole (PTZ) to completely kindle the mice in the PTZ control group. Gene expression changes in the A1Rs, potassium inwardly-rectifying channel 3.2 (Kir3.2), and ENT1 in the brain tissue samples of the mice following treatment with LEV were analyzed using reverse transcription-quantitative polymerase chain reaction, and immunohistochemistry was performed for the A1R protein expression. Docking studies predicted a significant interaction of LEV with A1Rs and ENT1 proteins. Results from the acute testing revealed that caffeine (100 mg/kg) and 8-cyclopentyl-1,3-dipropylxanthine (25 mg/kg) significantly reversed the antiseizure effects of LEV by reversing the percent protection and shortening the onset of the first myoclonic jerk (FMJ) and generalized clonic seizures (GCSs). In the PTZ-induced kindling, LEV demonstrated an increased gene expression of A1Rs and Kir3.2 in the brain. LEV also significantly reduced the gene expression of ENT1. Furthermore, the immunohistochemical analysis showed that LEV increased the protein expression of A1Rs in the brain. Based on these results, it can be concluded that LEV modulates epileptogenesis by acting on the adenosine pathway in the central nervous system.

DNA methylation regulates pancreatic gene expression and links maternal high-fat diet to the offspring glucose metabolism

Maternal high-fat diet (HFD) is related to an increased risk of glucose metabolism disorders throughout the whole life of offspring. The pancreas is a glucose homeostasis regulator. Accumulating evidence has revealed that maternal HFD affects offspring pancreas structure and function. However, the potential mechanism remains unclear. In this study, the mouse dam was fed with HFD or control diet (CD) during prepregnancy, pregnancy and lactation. The pancreatic insulin secretion function and islet genome methylome of offspring were analyzed. Pancreatic islet specific gene methylation was detected by using MeDIP qPCR. The results showed that body weight, blood glucose after oral glucose loads, fasting serum insulin, and HOMA-IR index values were significantly higher in male 12-week-old offspring from HFD dams than in the offspring from CD dams. Maternal HFD induced insulin secretion defects in male offspring. Compared with that in maternal CD group, methylation of the Abcc8 and Kcnj11 genes was increased in maternal HFD group in male offspring pancreatic islets. Furthermore, the expression levels of Abcc8 and Kcnj11 were downregulated by intrauterine exposure to a maternal HFD. In summary, maternal HFD results in a long-term functional disorder of the pancreas that is involved in insulin secretion-related gene DNA hypermethylation.

The W101C KCNJ5 Mutation Induces Slower Pacing by Constitutively Active GIRK Channels in hiPSC-Derived Cardiomyocytes.

Mutations in the KCNJ5 gene, encoding one of the major subunits of cardiac G-protein-gated inwardly rectifying K+ (GIRK) channels, have been recently linked to inherited forms of sinus node dysfunction. Here, the pathogenic mechanism of the W101C KCNJ5 mutation underlying sinus bradycardia in a patient-derived cellular disease model of sinus node dysfunction (SND) was investigated. A human-induced pluripotent stem cell (hiPSCs) line of a mutation carrier was generated, and CRISPR/Cas9-based gene targeting was used to correct the familial mutation as a control line. Both cell lines were further differentiated into cardiomyocytes (hiPSC-CMs) that robustly expressed GIRK channels which underly the acetylcholine-regulated K+ current (IK,ACh). hiPSC-CMs with the W101C KCNJ5 mutation (hiPSCW101C-CM) had a constitutively active IK,ACh under baseline conditions; the application of carbachol was able to increase IK,ACh, further indicating that not all available cardiac GIRK channels were open at baseline. Additionally, hiPSCW101C-CM had a more negative maximal diastolic potential (MDP) and a slower pacing frequency confirming the bradycardic phenotype. Of note, the blockade of the constitutively active GIRK channel with XAF-1407 rescued the phenotype. These results provide further mechanistic insights and may pave the way for the treatment of SND patients with GIRK channel dysfunction.

Patient-derived stem cell line UKMi005-A (hiPSC) harboring a non-synonymous heterozygous KCNJ5 gene variant

A published heterozygous gain-of-function variant in the KCNJ5 gene (p.Trp101Cys) encoding the G-protein-activated inward-rectifier potassium channel 4 subunit of the IK,ACh channel is associated with human sinus node dysfunction (SND). Differentiated hiPSC-cardiomyocytes may serve as an in-vitro model to study SND and to develop pharmacological rescue strategies. Therefore, a mutant hiPSCs line from patient-derived peripheral blood mononuclear cells (PBMCs) were reprogrammed with CytoTune-iPS 2.0 Sendai Reprogramming Kit. The hiPSC line (KCNJ5 K8) showed a regular karyotype, a typical hiPSC morphology, expressed pluripotency-associated markers in immunofluorescence stainings and RT-qPCR analysis. The ability for differentiation into all three germ layers was shown.

OR02-04 Peripheral Blood Steroid Profiling Discriminates Aldosterone-producing Adenoma Genotypes From Bilateral Primary Aldosteronism

Abstract Disclosure: A.F. Turcu: None. C. Lee: None. Z. Salman: None. H. Liu: None. A. Rabbah: None. S.M. Konzen: None. W.E. Rainey: None. T.J. Giordano: None. L. Zhao: None. A. Udager: None. Background: Primary aldosteronism (PA) is dichotomized into 2 major subtypes: unilaterally dominant PA, often caused by aldosterone-producing adenomas (APAs), and bilateral PA (BPA). Adrenal vein sampling (AVS)-guided unilateral adrenalectomy is often curative in patients with APA and offers marked cardiovascular and renal benefits. The diagnosis and subtyping of PA is a complex, multistep process, hindered by expertise and resource limitations. Objective: To develop steroid fingerprints that can distinguish genotype specific APAs from BPA in peripheral blood. Design And Methods: We enrolled 120 patients with PA who underwent AVS in a single tertiary referral center. Liquid-chromatography tandem mass spectrometry was used to simultaneously quantify 17 steroids in adrenal veins (AV) and periphery, both at baseline, and 10-20 min after cosyntropin stimulation. Aldosterone synthase (CYP11B2) immunohistochemistry-guided next generation sequencing was employed to identify aldosterone-driver mutations. Kruskal-Wallis tests were performed for comparison of continuous variables across multiple groups. Receiver operating characteristic (ROC) curves were plotted to discriminate APAs from BPA. Results: The 120 study participants included 75 patients with APA who underwent unilateral adrenalectomy and had documented aldosterone-driver mutations, and 45 patients with BPA. Of patients with APAs, 36 carried somatic mutations in CACNA1D, 24 in ATPase, and 15 in KCNJ5 genes, respectively. Patients with KCNJ5 mutations were younger and most were women. In the dominant AVs, the KCNJ5 group had marked elevations of 18-hydroxycortisol, 18-oxocortisol, aldosterone, and 11-deoxycorticosterone (DOC); conversely, the BB group had the lowest concentrations of mineralocorticoid and androgen precursors, despite comparable cortisol levels across all groups. Similar patterns were observed in peripheral blood. Linear discriminant analysis incorporating all steroids measured in baseline peripheral serum showed areas under the curve (AUC) of 0.98, 0.97, and 0.92 for distinguishing APAs with KCNJ5, ATPase, or CACNA1D mutations, respectively, from BPA. Conclusions: Single-assay steroid profiles measured in peripheral serum can distinguish genotype-specific APAs from BPA. Once validated, such tests might circumvent the need for AVS in large subset of PA patients. Presentation: Thursday, June 15, 2023

FRI125 Recurrence Of Primary Aldosteronism Long-Term After Adrenalectomy For Aldosterone-Producing Adenoma With KCNJ5 Gene Mutation: A Two-Cases Report

Abstract Disclosure: K. Aiga: None. M. Kometani: None. D. Aono: None. S. Karashima: None. T. Yoneda: None. Primary aldosteronism (PA) is a major cause of secondary hypertension. PA is known to have higher prevalence of cerebral or cardiovascular complications, indicating the importance of early detection and treatment for PA. PA is caused by autonomous secretion of aldosterone in the adrenal glands. PA is characterized by high plasma aldosterone concentration, low plasma renin activity and hypokalemia. PA is classified into unilateral PA (aldosterone-producing adenoma [APA] or unilateral hyperplasia) and bilateral PA (bilateral adrenal hyperplasia). PA with aldosterone excess in bilateral adrenal glands is defined as bilateral PA. On the other hand, PA with aldosterone excess in unilateral adrenal gland is defined as unilateral PA. Strategies for PA treatment depends on the subtype of PA. Medication by mineralocorticoid receptor antagonists is a common treatment for bilateral PA. Adrenalectomy is the most efficient treatment for unilateral PA. In general, patients tend to maintain normal serum potassium level and blood pressure after adrenalectomy, and recurrence of PA is extremely rare. Recently, mutation in the gene named KCNJ5 was found to derive APA. Herein, we report two cases of PA recurrence more than 10 years after surgical treatment for APA. Somatic mutation in KCNJ5 was detected in the first occurrence of PA in both cases. First case, a 52-year-old woman was examined for hypertension 22 years after total adrenalectomy of the right adrenal gland. Recurrent PA was diagnosed based on high aldosterone-renin-ratio (ARR), identification of left adrenal gland tumor by computed tomography (CT), and a confirmatory test. Second case, a 65-year-old man was examined for hypertension 17 years after total adrenalectomy of the left adrenal gland. He had maintained his blood pressure using medication since the onset of hypertension 4 years after the surgery. A year later, a high ARR was observed. PA recurrence was determined by a right adrenal gland tumor noted on CT and a confirmatory test. Tissues of the adrenal gland were obtained from adrenalectomy in both cases. Histopathological analysis revealed presence of one adenoma in the first case, while two adenomas were confirmed in the second case. Somatic mutation in KCNJ5 gene was detected in both cases. To date, there are no specific guidelines established for the management of recurrent PA. Early detection is crucial for the prevention of severe cardiovascular diseases. Long-term follow-up is recommended after the treatment of PA. Presentation: Friday, June 16, 2023

FRI157 Systematic Germline Genetic Analysis In A Cohort Of Adults With Primary Aldosteronism And Hypertension Onset ≤35 yo : Low Yield Of Genetic Pathogenic Variants

Abstract Disclosure: S. Parisien-La Salle: None. D. Nadine: None. Z. El-Haffaf: None. A. Lacroix: None. I. Bourdeau: None. Introduction: Primary aldosteronism (PA) is a common but underdiagnosed cause of hypertension. Although most cases are sporadic, up to 5% of patients have a familial form of PA. Current guidelines recommend germline genetic analysis in patients who present PA < 20 yo or have a family history of PA. As PA is underdiagnosed, we hypothesized that some patients with PA do not undergo germline genetic screening since familial history of PA is unrecognized. Objective: To evaluate the yield of systematic germline genetic analysis for familial PA in patients with PA, hypertension detection ≤ 35 yo and a family history of hypertension. Methods: From 2012-2022, patients diagnosed with PA (positive ARR and confirmatory testing), hypertension onset ≤ 35 yo and a family history of hypertension were offered genetic counselling for germline screening for known familial causes of PA. After informed consent, patients 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). Results: Twenty-five patients consented for genetic analysis. Thirteen patients (52%) were female. In regards to ethnic origin, 52% were French Canadians, 24% African-Americans and the other 24% was split between Asian, European and Middle Eastern descent. The mean age at diagnosis of hypertension was 28.3 yo and 39.7 yo at PA diagnosis. At PA diagnosis, 91.3% (21/23) had previous hypokalemia and 12% (3/25) a cortisol co-secretion (1 mg dexamethasone test> 50 nmol/L). Approximately 13% were on one hypertension drug, 30% on two, 26% on three, 26% on four and 5% were on five medications. Comobordities included: 8% atrial fibrillation, 20% obstructive sleep apnea and 4% coronary heart disease. All patients had a family history of hypertension, 5 patients (20%) had a family history of stroke, and 1 patient (4%) had a family history of PA. Of the patients who had already undergone adrenal vein sampling (n=22), 68.2% (15/22) underwent an adrenalectomy for lateralised aldosterone secretion and 31.8% (7/22) were treated with medical therapy for bilateral disease. None of the 24 patients who underwent testing for glucocorticoid-remediable aldosteronism were found to have the chimeric gene CYP11B2/CYP11B1. Twenty-three patients underwent the multigene panel and no pathogenic variants were identified. However, 4/23 (17,4%) patients carried a variant of unknown significance (VUS) in CACNA1H or CLCN2 genes (CACNA1H c.1315C>T(p.Arg439Cys),CACNA1H c.3868G>A(p.Val1290Ile),CACNA1H c.1939G>A (p.Gly647Ser), CLCN2 c.2402C>T, (p.Thr801Ile)). Conclusion: Systematic germline genetic testing for familial PA in this cohort of patients with PA, hypertension diagnosis ≤ 35 yo and a family history of hypertension did not yield positive results. Although PA is an underdiagnosed disease, familial forms remain very rare. Presentation: Friday, June 16, 2023

THU598 Pseudohypoaldosteronism Type 2: A New Variant Of A Rare Disease

Abstract Disclosure: T.L. Cater: None. L. Borges Espinosa: None. Introduction: Familial hyperkalemia and hypertension syndrome or pseudohypoaldosteronism type 2 (PH2) is a rare monogenic hypertension resulting from WNK1, WNK4, KLHL3, or CUL3 gene mutation. Subsequent interference at the Na-Cl co-symporter, epithelial Na, or ROMK channel results in metabolic acidosis, hyperkalemia, and hypertension responsive to thiazide treatment. This case demonstrates PH2 resulting from a KLHL3 gene variant not previously described. Mutations to KLHL3 decrease Na-Cl cotransporter expression in the distal convoluted tubule leading to increased sodium and chloride reabsorption, volume expansion, hypertension, and, therefore, less sodium available for potassium exchange in the collecting duct. Case Description: A 30-year-old female G1P0 with twin gestation was admitted at 33 weeks for preeclampsia with severe features. PMH was unremarkable. She underwent C-section and was discharged home with healthy twin daughters. BMP during admission showed hyperkalemia with peak potassium 5.2 mmol/L which improved to 4.6 mmol/L by discharge. Essential hypertension was diagnosed 3 months later (BP 130/90, 78 bpm, RR 16, BMI 30.0 kg/m2). Labetalol 50 mg BID was initiated. BMP obtained showed hyperkalemia as high as 6.4 mmol/L. Further workup showed undetectable renin with normal aldosterone, hyperchloremic metabolic acidosis with chloride 111 mmol/L and bicarbonate 20 mmol/L, and normal EKG. She was managed in the ED where her potassium improved to 5.1 mmol/L with persistent hyperchloremic metabolic acidosis. A diagnosis of pseudohyperkalemia was presumed initially. Labetalol was discontinued in favor of hydrochlorothiazide 12.5 mg daily. Lost to follow-up, she presented 10 years later to Endocrinology at age 41 for chronic hyperkalemia and hyperchloremic metabolic acidosis. Labs showed potassium 6.5 mmol/L, chloride 108 mmol/L, and bicarbonate 23 mmol/L. Exam showed BP 133/98, BMI 26.63 kg/m2. She recounted several ER visits over the past decade for hyperkalemia with highest reported potassium of 7.8. She had stopped her thiazide due to dizziness, palpitations, and fatigue. Family history was now notable for hyperkalemia in her father, two brothers, and fraternal niece but no genetic testing was available. We resumed hydrochlorothiazide 12.5 mg every other day; follow-up labs showed improved potassium 5.2 mmol/L. Genetic testing revealed heterozygosity in the KLHL3 gene for the c.1064T &gt G sequence, a variant that has not been reported in the literature or large population database. Conclusion: Hypertension in PH2, distinct in its presentation with hyperkalemia and metabolic acidosis, requires a detailed family history and hormonal evaluation to make the diagnosis. Genetic testing in our case patient revealed a variant at the KLHL3 gene not previously described, underscoring the utility of genetic testing in understanding this rare condition. Presentation: Thursday, June 15, 2023

THU228 Thyrotoxic Periodic Paralysis In Three Adolescent Males

Abstract Disclosure: E. Ra: None. J. Austin: None. Thyrotoxic periodic paralysis (TPP) is a rare but potentially fatal complication of hyperthyroidism associated with Graves disease. Paralysis is due to hypokalemia caused by overactivation of the sodium potassium adenosine triphosphatase (Na+/K+ ATPase). TPP is usually seen in males between 20 - 40 years of age who are of Asian descent. We report 3 Hispanic American adolescent males, as young as 13 years old, who presented with TPP without an existing diagnosis of Graves disease. All three presented with leg weakness and were found to be hypokalemic and ultimately diagnosed with hyperthyroidism. Each patient was supplemented with potassium, either intravenously or orally, with their symptoms resolving within 24 hours. Although TPP is most prevalent in Asian adult males, theorized to be due to an underlying genetic preposition related to a variant of the KCNJ18 gene, there are increasing reports of non - Asian adolescents presenting in TPP. Therefore, pediatric care providers should consider TPP in their differential if a patient presents with weakness and hypokalemia, even without a pre-existing diagnose of hyperthyroidism. Presentation: Thursday, June 15, 2023

FRI550 Case Of Thyrotoxic Periodic Paralysis In African American Man With Cannabis Use

Abstract Disclosure: H. Al Jumaili: None. A. Mahaldar: None. S. Campbell: None. A. Gosmanova: None. Introduction: Recent changes in cannabis use (CU) laws led to growing interest in its use for recreational and therapeutic purposes. may have serious health problems such as hypokalemia, paralysis and rhabdomyolysis. Thyrotoxic Periodic Paralysis (TPP) is a rare and life-threatening complication of the thyrotoxicosis characterized by acute reversable painless muscle weakness or paralysis and hypokalemia due to massive intracellular shift of potassium. This condition is mainly seen males of Asian descent. Case: A 31-year-old African American man with Graves’ disease admitted to the hospital for upper and lower extremities weakness after Thanksgiving Day. He woke up with sudden inability to move any of his extremities with. He had high carbohydrate meal, on the evening. Patient reported having similar periodic episodes of paralysis, usually worse in the lower extremities for the last 2 years. This episode lasted longer than usual. On exam, he had enlarged thyroid gland and tachycardia. motor weakness, worse on lower extremities, hyporeflexia and intact sensation. Potassium was 1.8 mmol/l, magnesium 1.5 mg/dl, TSH <0.01 mIU/ml, FT4 4.3 ng/dl, FT3 18.3 ng/dl, anti-thyroid antibodies were elevated at 18 IU/L, and urine screen was positive for cannabinoid. Potassium was replaced, he was given propranolol and continued on methimazole. Patient's paralysis had improved in all four limbs, with serum potassium of 4.1 mmol/L. Discussion: TPP is a rarely seen condition in US but is known in an eastern Asian population, and in US the incidence rate was reported to be around 0.1 to 0.2%. American Indian are thought to be the higher risk. Underlying mechanism is imbalance in potassium homeostasis due to increased cellular Na-K ATPase pump activity with shift of potassium to the intracellular space. There are many theories regarding the cause of exaggerated intracellular potassium influx in TPP. Na-K ATPase activity is directly stimulated by thyroid hormone and insulin response to carbohydrate ingestion which promotes potassium uptake into muscle correlating with clinical observation that paralysis seen after a high carbohydrate meal. KCNJ18 gene mutations which alter the function of an inwardly rectifying potassium channel named Kir2.6 have been detected in some patients. In our patient, additional factor such as cannabis use potentiated intracellular potassium shift and hypokalemia. Recent evidence suggests that the CB1 receptor is expressed not only in the brain, but also found in lungs, heart, and skeletal muscle. Stimulation of (CB1) and activation of G protein-coupled inwardly rectifying potassium (GIRK) channels through intra-cellular signal cascades promotes hypokalemia and paralysis. Conclusion: This case raises awareness of TPP in non-Asian population and highlights the importance to consider cannabis as additional trigger for hypokalemia and paralysis. Presentation: Friday, June 16, 2023

Nonviral base editing of KCNJ13 mutation preserves vision in a model of inherited retinal channelopathy.

Clinical genome editing is emerging for rare disease treatment, but one of the major limitations is the targeting of CRISPR editors' delivery. We delivered base editors to the retinal pigmented epithelium (RPE) in the mouse eye using silica nanocapsules (SNCs) as a treatment for retinal degeneration. Leber congenital amaurosis type 16 (LCA16) is a rare pediatric blindness caused by point mutations in the KCNJ13 gene, a loss of function inwardly rectifying potassium channel (Kir7.1) in the RPE. SNCs carrying adenine base editor 8e (ABE8e) mRNA and sgRNA precisely and efficiently corrected the KCNJ13W53X/W53X mutation. Editing in both patient fibroblasts (47%) and human induced pluripotent stem cell-derived RPE (LCA16-iPSC-RPE) (17%) showed minimal off-target editing. We detected functional Kir7.1 channels in the edited LCA16-iPSC-RPE. In the LCA16 mouse model (Kcnj13W53X/+ΔR), RPE cells targeted SNC delivery of ABE8e mRNA preserved normal vision, measured by full-field electroretinogram (ERG). Moreover, multifocal ERG confirmed the topographic measure of electrical activity primarily originating from the edited retinal area at the injection site. Preserved retina structure after treatment was established by optical coherence tomography (OCT). This preclinical validation of targeted ion channel functional rescue, a challenge for pharmacological and genomic interventions, reinforced the effectiveness of nonviral genome-editing therapy for rare inherited disorders.

Molecular genetic diagnosis and treatment of congenital hyperinsulinism: results of observation of patients with variants in the genes <i>ABCC8</i> and <i>KCNJ11</i>

Congenital hyperinsulinism is a rare hereditary disease characterized by inadequate hypersecretion of insulin by pancreatic -cells, clinically manifested by persistent hypoglycemia, which poses a great threat to patient survival and a high risk of developing severe neurological complications.
 The article presents the results of clinical, hormonal and molecular genetic examination and treatment of 10 patients with congenital hyperinsulinism caused by mutations in the genes of ATP-dependent potassium channels (KCNJ11, ABCC8), hospitalized in Saint Petersburg State Pediatric Medical University clinic in 20102023. In all the studied patients, the disease manifested from the 1st to the 3rd day of life, and the median age of diagnosis of congenital hyperinsulinism in the study group was 1 month (min 14 days; max 3 years 9 months). In 8 out of 10 patients, a severe course of hypoglycemic syndrome was noted at the onset of the disease. According to the molecular genetic investigation results, 8 different mutations were identified: in the KCNJ11 (2/8) and ABCC8 (6/8) genes. Identical variants were found in two pairs of related patients. In children with mutations in the ABCC8 gene (n = 8), 2 variants with unknown clinical significance were identified, which were not previously described in allelic databases and scientific literature. According to the analysis of anamnestic and clinical and laboratory data, 80.0% of children, including patients with new, previously not described in the scientific literature, variants in the ABCC8 gene have a severe progressive course of congenital hyperinsulinism, requiring the appointment of insulinostatic therapy.

Andersen-Tawil Syndrome Associated with Cerebral Cavernoma: Challenge and Diagnostic Delay of a Multisystemic Disease

Introduction: Andersen-Tawil Syndrome (ATS) is a rare dominantly inherited disorder caused by mutations in the KCNJ2 gene; it presents with cardiac arrhythmias and periodic muscle paralysis

Andersen-Tawil Syndrome Associated with Cerebral Cavernoma: Challenge and Diagnostic Delay of a Multisystemic Disease

Introduction: Andersen-Tawil Syndrome (ATS) is a rare dominantly inherited disorder caused by mutations in the KCNJ2 gene; it presents with cardiac arrhythmias and periodic muscle paralysis

Clinical Findings and Genetic Analysis of Nine Mexican Families with Bartter Syndrome

Bartter's syndrome (BS) is a group of salt-wasting tubulopathies characterized by hypokalemia, metabolic alkalosis, hypercalciuria, secondary hyperaldosteronism, and low or normal blood pressure. Loss-of-function variants in genes encoding for five proteins expressed in the thick ascending limb of Henle in the nephron, produced different genetic types of BS. Clinical and genetic analysis of families with Antenatal Bartter syndrome (ABS) and with Classic Bartter syndrome (CBS). Nine patients from unrelated non-consanguineous Mexican families were studied. Massive parallel sequencing of a gene panel or whole-exome sequencing was used to identify the causative gene. Proband 1 was homozygous for the pathogenic variant p.Arg302Gln in the SLC12A1 gene encoding for the sodium-potassium-chloride NKCC2 cotransporter. Proband 3 was homozygous for the nonsense variant p.Cys308* in the KCNJ1 gene encoding for the ROMK potassium channel. Probands 7, 8, and 9 showed variants in the CLCKNB gene encoding the chloride channel ClC-Kb: proband 7 was compound heterozygous for the deletion of the entire gene and the missense change p.Arg438Cys; proband 8 presented a homozygous deletion of the whole gene and proband 9 was homozygous for the nonsense mutation p.Arg595*. A heterozygous variant of unknown significance was detected in the SLC12A1 gene in proband 2, and no variants were found in SLC12A1, KCNJ1, BSND, CLCNKA, CLCNKB, and MAGED2 genes in probands 4, 5, and 6. Genetic analysis identified loss-of-function variants in the SLC12A1, KCNJ1, and CLCNKB genes in four patients with ABS and in the CLCNKB gene in two patients with CBS.

A case of permeant neonatal diabetes with KCNJ11 mutation

Neonatal diabetes mellitus is considered when there is hyperglycaemia requiring insulin therapy. Phenotypically NDM is classified into three types-transient, permanent and syndromic forms. Permanent NDM-may start in new-born life and is mainly due single gene mutations-KCNJ11 and ABCC8. This mutation is almost 90% manageable with oral sulphonyl ureas. We report a case of Permanent NDM with KCNJ11 mutation who presented in diabetic Ketoacidosis at 4 months of age. Clinical genome sequencing revealed a heterozygous missense variation in exon 1 of the KCNJ11 gene (chr11: g.17387491G>A) that results in the amino acid substitution of cysteine for arginine at codon 201. She was initially treated with insulin for which she had poor glycaemic control. She responded well following the switch over to sulphonylureas with good compliance and has normal development.

Clinical features and genetic analysis of a child with EAST/SeSAME syndrome

To explore the genetic basis for a EAST/SeSAME syndrome child featuring epilepsy, ataxia, sensorineural deafness and intellectual disability. A child with EAST/SeSAME syndrome who had presented at the Third Affiliated Hospital of Zhengzhou University in January 2021 was selected as the study object. Peripheral blood samples of the child and her parents were collected and subjected to whole exome sequencing. Candidate variants were verified by Sanger sequencing. Genetic testing revealed that the child has harbored compound heterozygous variants of the KCNJ10 gene, namely c.557T>C (p.Val186Ala) and c.386T>A (p.Ile129Asn), which were inherited from her mother and father, respectively. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were predicted as likely pathogenic (PM1+PM2_Supporting+PP3+PP4; PM1+PM2_Supporting+PM3+PP3+PP4). The patient was diagnosed with EAST/SeSAME syndrome due to the compound heterozygous variants of the KCNJ10 gene.