Mutations In SLC26A4 Gene Research Articles

Correction of the pathogenic mutation in the deafness gene SLC26A4 via prime editor and adenine base editor in vitro

Objective: To investigate the feasibility of in vitro prime editor (PE) and adenine base editor (ABE) for correction the pathogenic variant of the human deafness gene SLC26A4 c.1229C>T. Methods: From March 2023 to April 2024, prime editing guide RNA (pegRNA) expression vectors as well as single guide RNA (sgRNA) were designed and constructed for the SLC26A4 c.1229C>T variant, and the feasibility of correction was performed in the HEK293T mutation model, the correction efficiency was analyzed by deep sequencing. Results: A mutant cell model of SLC26A4 c.1229C>T was successfully established. Correction was achieved in the SLC26A4 c.1229C>T mutant cell model using PE and ABE8e. Deep sequencing analysis revealed the correction efficiencies of (31.89±0.77)% and (41.07±2.28)%, respectively. Conclusion: In this study, a new base correction strategy based on the human deafness gene SLC26A4 is proposed, which provides a viable reference for gene therapy of deafness caused by SLC26A4 gene mutation.

Preimplantation genetic testing for a Chinese pedigree affected with Primary carnitine deficiency

To investigate the results of preimplantation genetic testing for monogenic diseases (PGT-M) in a Chinese pedigree affected with Primary carnitine deficiency (PCD). A pedigree affected with PCD who visited Hainan Women and Children's Medical Center in April 2023 due to "SLC22A5 gene mutation found in offspring genetic testing and preparing for a second child" was selected as the study subject. Pathogenicity of the proband's variant sites was determined by referring to the Standards and Guidelines for the Interpretation of Sequence Variants established by the American College of Medical Genetics and Genomics (ACMG). Sanger sequencing was used to verify the variant sites of SLC22A5 gene in the proband and her parents, and the single nucleotide polymorphism (SNP) haplotype of the family was constructed by SNP microarray (SNP array) method to determine the carrier status of pathogenic genes. After fertilization via assisted reproductive technology, whole genome amplification (WGA) was performed on the biopsied trophoblastic cells. Sanger sequencing, next-generation sequencing (NGS), and SNP array techniques were then used to detect the variants in the SLC22A5 gene and chromosome copy number variation (CNV) in the embryos. Embryos without the variants were selected for transferring. After the successful pregnancy of the proband's mother, amniocentesis was not performed for prenatal diagnosis due to repeated vaginal bleeding. After delivery, neonatal peripheral blood sample was collected to verify the results of PGT-M, and follow-up was conducted. This study was reviewed and approved by the Medical Ethics Committee of Hainan Women and Children's Medical Center (Ethics No. HNWCMC-2022-178). In this study, the c.338G>A and c.760C>T variants in SLC22A5 gene were evaluated as pathogenic variants. Sanger sequencing results of this family showed that the c.338G>A and c.760C>T variants of the proband were inherited from his father and mother, respectively. Haplotypes of c.338G>A and c.760C>T variants of SLC22A5 gene were successfully constructed. PGT-M results showed that 2 of the 8 blastulas biopsied failed WGA, and the CNV detection results of the remaining 6 blastocysts were all euploid: 2 had no mutations in the SLC22A5 gene, 3 were single heterozygous carriers of paternal or maternal origin, and 1 was compound heterozygous carriers of paternal and maternal origin. Combined with the embryo morphology score, an intrauterine singleton pregnancy was achieved after the successful transfer of an optimal embryo with no CNV abnormalities and no paternal or maternal SLC22A5 gene mutations, resulting in the birth of a healthy female baby at 38+3 weeks of gestation. The results of peripheral blood chromosomal karyotyping analysis, CNV detection and SLC22A5 gene c.338G>A and c.760C>T site variant detection of the infant were consistent with those of PGT-M, and no abnormality was found. PGT-M had helped the couple carrying SLC22A5 gene variant to have a healthy offspring and effectively blocked the transmission of PCD in this family.

A novel duplication mutation of SLC2A1 gene causing glucose transporter 1 deficiency syndrome

A novel duplication mutation of SLC2A1 gene causing glucose transporter 1 deficiency syndrome

Variability in Inner Ear Morphology Among a Family With Pendred Syndrome Due to a SLC26A4 Gene Variant.

Pendred syndrome, an autosomal recessive disorder, is often associated with pathogenic variants of the SLC26A4 gene that encodes the pendrin protein. Given its autosomal recessive inheritance, tracing the family history and screening siblings become crucial once a diagnosis of Pendred syndrome is confirmed. This case report aims to underscore the variability in inner ear morphology within a family diagnosed with Pendred syndrome, all carrying the same SLC26A4 gene mutation. A chart review and a review of the literature. We present a family of 4, all of whom possess sensorineural hearing loss due to the same homozygous SLC26A4 variant c.919-2A>G. Intriguingly, clinical manifestations, especially inner ear deformities, displayed variability among family members. Notably, 1 family member exhibited a normal cochleovestibular structure morphology, which was rarely reported in the literature. This report highlights the significance of genetic testing and familial consultation when a proband exhibits typical Pendred syndrome symptoms. It also underscores that the inner ear morphology can exhibit variability among family members, even with the same homozygous SLC26A4 variant.

Analysis of 59 cases of large vestibular aqueduct syndrome SLC26A4gene mutation frequency and new mutation sites

Objective:To study the frequency of SLC26A4 gene mutation sites in children with enlarged vestibular aqueduct deafness in Yunnan, report the new mutation sites of SLC26A4 gene, further clarify the mutation spectrum of SLC26A4gene, and explore the association between biallelic and monoallelic mutations of SLC26A4 gene and CT phenotype of inner ear, so as to provide basis for clinical and genetic diagnosis of deafness. Methods:Review the results of temporal bone CT examination of 390 children after cochlear implantation in the Department of Otolaryngology, Kunming Children's Hospital from August 2016 to September 2021. Sanger sequencing of SLC26A4 gene was performed in 59 children with enlarged vestibular aqueduct. According to the genetic test results, the children who underwent temporal bone CT examination were divided into two groups: SLC26A4 biallelic mutation group（homozygous mutation and compound heterozygous mutation）, monoallelic mutation group, and the association with inner ear CT phenotype was analyzed, and the new sites were summarized and analyzed. Results:The c.919-2a>g mutation was the most common mutation in children with enlarged vestibular aqueduct with SLC26A4 gene mutation. Three new variants of SLC26A4 gene were found; CT examination combined with genetic testing found that a part of children with enlarged vestibular aqueduct was associated with SLC26A4 monoallelic mutation or no SLC26A4 gene mutation was detected. Further research is needed to investigate the involvement of other pathogenic factors in the pathogenesis of EVA.

Analysis of clinical and genetic variation in neonatal intrahepatic cholestasis caused by citrin deficiency

Objective: To investigate the clinical phenotype and gene variation conditions in neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD), so as to provide a basis for genetic counseling and clinical diagnosis and treatment of the family. Methods: 11 cases of neonatal intrahepatic cholestasis who visited the Children's Hospital Affiliated to Zhengzhou University between February 2019 and March 2021 were selected as the study subjects. High-throughput sequencing technology was used to detect the gene variation condition in 11 neonatal patients and 100 normal control neonates. The suspicious loci and family members were verified by Sanger sequencing and QPCR technology. Results: All 11 children with NICCD had different degrees of jaundice and liver damage symptoms, combined with coagulation dysfunction and anemia (n = 7), cardiac malformation (n = 2), elevated myocardial enzymes (n = 4), hyperlipidemia (n = 1), hyperkalemia (n = 1), persistent diarrhea (n = 3), developmental delay (n = 1). A total of 10 different types of SLC25A13 gene mutations were detected in 11 cases, including three frameshift mutations, two splicing changes, two missense mutations, one intron insertion, one nonsense mutation, and one heterozygous deletion. After reviewing literature and databases, c.1878delG(p.I627Sfs*73) and exon11 deletion were novel mutations that had not been reported at home or abroad. Conclusion: The clinical features of NICCD are non-specific, and genetic testing aids in the early and accurate diagnosis of the disease, providing an important basis for clinical treatment and genetic counseling for family members. In addition, the detection of novel mutation sites has enriched the SLC25A13 gene variation spectrum.

A Case Report on Recurrent Episodes of Dyselectrolytemia Diagnosed as Gitleman Syndrome

Background: Gitleman syndrome (GS) is also known as familial hypokalaemia-hypomagnesemia, which is a rare genetic disorder. It is an autosomal recessive disease that is characterized by hypokalaemia, hypomagnesemia, metabolic alkalosis, hypocalciuric hypercalcemia and hyperaldosteronism.
 Case Report: 70-year-old female patient who was diagnosed with Gitelman syndrome with the symptoms of loss of appetite, muscle weakness, and abdominal pain. Electrolyte levels were low. After inconclusive evidence from laboratory investigation, genetic testing was performed. The detection of the SLC12A3 gene mutation encoding thiazide diuretic sensitive sodium chloride cotransporter located in DCT of kidney, confirmed the diagnosis of GS with c.1331delA variant. No pathological variant of CLCNKB for Bartter syndrome has been found. The patient was treated with parenteral normal saline, potassium chloride, Arachitol, spironolactone, metoclopramide, and MgD3 (magnesium glycinate and vitamin D3), the symptoms was significantly relieved. After discharge the intravenous medicines were shifted to oral and followed up with serum electrolyte levels in our institute.

The correlation between deafness progression and SLC26A4 mutations in enlarged vestibular aqueduct patients.

The relationship between the hearing phenotype and the SLC26A4 mutation in enlarged vestibular aqueduct cases has not been fully elucidated. To detect SLC26A4 mutation in a group of cases with enlarged vestibular aqueduct who received cochlear implantation and to analyze the correlation between the SLC26A4 genotype and the progression of deafness. Twenty-nine enlarged vestibular aqueduct patients were selected. Using the Sanger sequence to analyze SLC26A4 gene mutations. The 29 cases were divided into group A (carrying the c.919-2A > G mutation) and group B (not carrying the c.919-2A > G mutation). The difference in the duration of deafness was analyzed between the two groups. The detection rate of the c.1174A > T mutation in the postlingual deafness group was 37.5%, higher than that in the prelingual deafness group (0%). The difference in the duration of deafness between groups A and B was not statistically significant by the Mann-Whitney U test (p > 0.05). The correlation between the SLC26A4 genotype and the duration of deafness in cases with enlarged vestibular aqueduct is not yet clear. However, the c.1174A > T mutation may be linked to delayed hearing loss and the progression of deafness may be relatively slow in some cases of c.919-2A > G mutation.

Citrin Deficiency: Clinical and Nutritional Features.

SLC25A13 gene mutations are responsible for diseases related to citrin deficiency (CD), such as neonatal intrahepatic cholestasis caused by citrin deficiency and adult-onset type II citrullinemia (CTLN2). From childhood to adulthood, CD patients are apparently healthy due to metabolic compensation with peculiar dietary habits-disliking high-carbohydrate foods and liking fat and protein-rich foods. Carbohydrate overload and alcohol consumption may trigger the sudden onset of CTLN2, inducing hyperammonemia and consciousness disturbance. Well-compensated asymptomatic CD patients are sometimes diagnosed as having non-obese (lean) non-alcoholic fatty liver disease and steatohepatitis, which have the risk of developing into liver cirrhosis and hepatocellular carcinoma. CD-induced fatty liver demonstrates significant suppression of peroxisome proliferator-activated receptor α and its downstream enzymes/proteins involved in fatty acid transport and oxidation and triglyceride secretion as a very low-density lipoprotein. Nutritional therapy is an essential and important treatment of CD, and medium-chain triglycerides oil and sodium pyruvate are useful for preventing hyperammonemia. We need to avoid the use of glycerol for treating brain edema by hyperammonemia. This review summarizes the clinical and nutritional features of CD-associated fatty liver disease and promising nutritional interventions.

Postnatal genetic umbilical cord analysis for earliest possible detection of inherited hearing impairment

IntroductionThe most common sensorineural disorder in humans is hearing impairment and approximately 60% of prelingual hearing disorders are genetic. Especially parents with a congenital deaf child want to know as early as possible whether their second born child has the same genetic defect or not. The aim of this study is to demonstrate that postnatal genetic umbilical cord analysis is both the earliest detection possibility and sufficient.MethodsWe included first born children with severe hearing impairment that underwent cochlear implantation. All included patients were analyzed genetically and exhibited mutations of either DFNB1 loci or SLC26A4 gene. Additionally, the umbilical cord of the sibling underwent genetic analysis to detect hereditary genetic mutations as early as possible.Results49 newborn children out of 22 families were included in this study. Genetic analysis revealed clinical relevant mutations in all first born children and in four siblings via umbilical cord analysis. All patients who have been diagnosed with a relevant genetic mutation that caused severe hearing impairment underwent hearing rehabilitation via cochlear implant surgery.ConclusionThis study demonstrates the sufficient and early as possible detection of known genetically hearing disorders via umbilical cord analysis. In case of a known familial genetic hearing disorder, it is advisable to analyze newborn siblings for the corresponding genetic defect as soon as possible, to be able to plan and initiate clinical care for the patient as early as possible. It is also extremely important for the parents to obtain clear information about the auditory status of the newborn.

An induced pluripotent stem cell line (MUSIi019-A) generated from a patient with distal renal tubular acidosis carrying a compound heterozygous mutation in solute carrier family 4 member 1 (SLC4A1) gene

Distal renal tubular acidosis (dRTA), a disease characterized by the failure of the distal nephron to secrete acid into the urine, can be caused by mutations in SLC4A1 gene encoding erythroid and kidney anion exchanger 1 (AE1). Here, an induced pluripotent stem cell (iPSC) line was generated from a patient with dRTA and hemolytic anemia carrying compound heterozygous SLC4A1 mutations containing c.1199_1225del (p.Ala400_Ala408del), resulting in Southeast Asian ovalocytosis (SAO), and c.1331C>A (p.Thr444Asn). Peripheral blood mononuclear cells (PBMCs) were reprogrammed using Sendai viral reprogramming. The established iPSC line, MUSIi019-A, exhibited pluripotent property and retained the same mutations observed in the patients.

Vestibular Loss in Children Affected by LVAS and IP2 Malformation and Operated with Cochlear Implant.

This is a single center cohort study regarding the prevalence of vestibular loss in hearing impaired children affected by large vestibular aqueduct syndrome (LVAS) with incomplete cochlear partition malformation type II (IP2), fitted with cochlear implant (CI). Twenty-seven children received CI operations at 0.4-13 years on one or both ears and tested for vestibular loss with head impulse test, video head impulse test, mini ice-water test and cervical VEMP. Vestibular loss was found in 19% of operated ears and in 13.9% of non-operated ears. The difference was not statistically significant and was not significantly modified by age at implantation, age at testing, sex, presence of SLC26A4 gene mutation or bilaterality. However, the presence of anatomic anomalies at the level of the vestibulum or semicircular canals was significantly associated with a higher incidence of vestibular loss in CI operated children but not in those non-operated. No other factors, such as the surgical access, the electrode type, the presence of Gusher perioperatively, or post-operative vertigo modified significantly the prevalence of vestibular loss. In conclusion, LVAS/IP2 appears to be the major determinant of vestibular loss in these children, with a less obvious impact of CI, excluding the cases with vestibulum/canal anomalies: this group might have a higher risk for vestibular loss after CI surgery.

CRISPR-Cas9-Mediated Correction of SLC12A3 Gene Mutation Rescues the Gitelman's Disease Phenotype in a Patient-Derived Kidney Organoid System.

The aim of this study is to explore the possibility of modeling Gitelman's disease (GIT) with human-induced pluripotent stem cell (hiPSC)-derived kidney organoids and to test whether gene correction using CRISPR/Cas9 can rescue the disease phenotype of GIT. To model GIT, we used the hiPSC line CMCi002 (CMC-GIT-001), generated using PBMCs from GIT patients with SLC12A3 gene mutation. Using the CRISPR-Cas9 system, we corrected CMC-GIT-001 mutations and hence generated CMC-GIT-001corr. Both hiPSCs were differentiated into kidney organoids, and we analyzed the GIT phenotype. The number of matured kidney organoids from the CMC-GIT-001corr group was significantly higher, 3.3-fold, than that of the CMC-GIT-001 group (12.2 ± 0.7/cm2 vs. 3.7 ± 0.2/cm2, p < 0.05). In qRT-PCR, performed using harvested kidney organoids, relative sodium chloride cotransporter (NCCT) mRNA levels (normalized to each iPSC) were increased in the CMC-GIT-001corr group compared with the CMC-GIT-001 group (4.1 ± 0.8 vs. 2.5 ± 0.2, p < 0.05). Consistently, immunoblot analysis revealed increased levels of NCCT protein, in addition to other tubular proteins markers, such as LTL and ECAD, in the CMC-GIT-001corr group compared to the CMC-GIT-001 group. Furthermore, we found that increased immunoreactivity of NCCT in the CMC-GIT-001corr group was colocalized with ECAD (a distal tubule marker) using confocal microscopy. Kidney organoids from GIT patient-derived iPSC recapitulated the Gitelman's disease phenotype, and correction of SLC12A3 mutation utilizing CRISPR-Cas9 technology provided therapeutic insight.

The effect of SLC26A4 gene mutations on long-term rehabilitative outcomes in cochlear implant patients

Background SLC26A4 gene mutations related to hearing loss patients can obtain good hearing and speech rehabilitation effects after cochlear implantation (CI). Objective To explore the long-term rehabilitative outcomes of CI in patients with different SLC26A4 mutation groups. Material and Methods Clinical data of 71 patients with SLC26A4 gene mutations who received CI in the Second Hospital of Lanzhou University from 2012 to 2015 were retrospectively reviewed. According to the genetic test results, use One-way ANOVA analysis to compare the differences in auditory results, categories of auditory performance (CAP) and speech intelligibility rating (SIR) index questionnaire scores and speech recognition rates among different groups in 4-5 years after CI. Result Compared with other genotypes of SLC26A4, the patients with homozygous mutation of c.919-2A > G in SLC26A4 had better hearing aid threshold at 500 Hz and better recognition rates of Yangyang words than other monoallelic mutation groups after CI (p < .05). Conclusions and Significance The most common hot spot mutation of SLC26A4 gene is c.919-2A > G. The patients with homozygous mutation of c.919-2A > G in SLC26A4 gene had partly better hearing and speech rehabilitation than other monoallelic mutation groups after CI.

Annals of Clinical and Medical Case Reports

1.1. Objective: Gitelman syndrome (GS) is an autosomal recessive tubular disorder characterized by metabolic alkalosis, hypokalemia, hypomagnesemia and hypocalciuria. GS is mostly caused by inactivating mutations of the SLC12A3 gene. The purpose of this study was to describe the clinical features of a GS patient and investigate the underlying mutations of SLC12A3 gene in the pedigree. 1.2. Methods: A patient suffering from muscle weakness was clinically diagnosed as GS. Clinical data of the proband were studied retrospectively. All of his family members were screened for SLC12A3 gene mutations. 26 exons and exon-intron boundaries of SLC12A3 gene were amplified by Polymerase Chain Reaction(PCR). PCR products were sequenced directly. 1.3. Results: The proband had hyperreninemia but hypoaldosteronemia, which was distinct from the cases previously reported. The proband and his sick brother were found to have the same compound heterozygous mutations (c.917C&gt;T and IVS 14-8T&gt;C) of SLC12A3 gene. Each mutation was detected in paternal and maternal genomic DNA, respectively. The proband’s healthy brother had one mutation (c.917C&gt;T) only. IVS 14-8T&gt;C was a novel splicing site mutation that had never been reported. 1.4. Conclusion: Hypoaldosteronemia was found in a GS patient. A novel heterozygous splicing site mutation of the SLC12A3 gene was reported, expanding the spectrum of SLC12A3 gene mutations.

Novel SLC12A3 gene mutations and clinical characteristics in two pedigrees with Gitelman syndrome.

Gitelman syndrome (GS) is an autosomal recessive tubulopathy resulting from inactivating mutations in the SLC12A3 gene that encodes the thiazide-sensitive sodium-chloride cotransporter (NCC). To date, more than 500 mutations have been identified in the SLC12A3 gene. In this study, we identified two new mutations in the SLC12A3 gene in two Chinese GS pedigrees. The clinical characteristics and laboratory examination of two suspected GS patients in our hospital were analyzed. In addition, two pedigrees including 11 members and 2 patients underwent SLC12A3 gene analysis. Both patients were middle-aged women with characteristics of hypokalemic metabolic alkalosis, hypomagnesemia, low level of urinary calcium and the elevated levels of renin-angiotensin-aldosterone system. So, they were clinically diagnosed as GS. Patient 2 also had type 2 diabetes and Graves'disease. Both patients were found to carry two mutations of SLC12A3 gene by Sanger direct sequencing, which were all compound heterozygous mutations. We identified three mutations in these two Chinese GS pedigrees, one of which was c.179C>T (Thr60Met). The novel c.2159G>T (p. Gly720Val) and c.2675T>C (p. Leu892Pro) mutations were strongly predicted to be pathogenic using four network programs-Polyphen-2, SIFT, Mutation Taster and LRT. We identified two novel SLC12A3 genetic variant [c.2159G>T (p.Gly720Val) and c.2675T>C (p.Leu892Pro)] in two Chinese GS pedigrees. The discovery of new mutations has enriched the spectrum of SLC12A3 genotypes.

Clinico- radiological profile of genetically proven Complicated Hereditary Spastic Paraparesis: A case series

Complicated Hereditary Spastic Paraparesis (HSP) is a group of heterogenous neurodegenerative disease characterized by progressive spastic paraparesis with additional features like cognitive impairment, seizures, movement disorders, visual loss, deafness, peripheral neuropathy, and pes cavus. There have been few case series reported in literature from India. We herein report four cases of complicated HSP. Four (three females and 1 male) patients of genetically confirmed HSP with a mean age of onset 10.5 years were recruited. There was mean delay of 8 years in reaching diagnosis. MRI brain showed thinning of corpus callosum in three patients and Ear of lynx sign in two patients. Next Generation Clinical Exome Sequencing confirmed mutations in SPG11 gene in three patients and SLC2A1 in one patient. SPG11 gene mutations were the most frequent genetic abnormality with SLC2A1 gene mutation in single patient. Genetically confirmed diagnosis helps in prognostication and genetic counselling.

Correlation of temporal bone HRCT, SLC26A4 gene and hearing loss in enlarged vestibular aqueduct

Objective:To explore the correlation between high-resolution computed tomography（HRCT） of temporal bones, SLC26A4 gene mutation and hearing loss in patients with enlarged vestibular aqueduct（EVA）. Methods:The medical records of 257 subjects hospitalized for moderate to severe sensorineural hearing loss in the Department of Otolaryngology Head and Neck Surgery, Hainan General Hospital between May 2018 to 2021 were retrospectively reviewed. All included cases received audiological examination, HRCT scanning of temporal bones and SLC26A4 gene sequencing. According to the Valvassori standard, cases with the diameter from the common peduncle of the semicircular canal to the midpoint of the outer orifice of the vestibular aqueduct（MP） over 1.5 mm, or the diameter of the outer orifice of the vestibular aqueduct（OP） more than 2.0 mm were diagnosed as EVA. There were 22 cases（44 ears） of EVA in the study, aged between 6 months to 17 years old. Based on the hearing changes at birth and during growth, 18 ears of which were classified into the stable hearing group, while the other 26 ears in the unstable group. Moreover, all involved cases were grouped by MP（1.5 to <3.0 mm and ≥3.0 mm） and OP（2.0 to <4.0 mm and ≥4.0 mm）. SPSS 25.0 software was applied in the study. The correlation between hearing loss and MP and OP was analyzed. The results of HRCT of temporal bones and SLC26A4 gene sequencing were compared as well. Results:Though the size of MP and OP was not statistically different between the stable and hearing groups in EVA ears（P>0.05）, it was significantly correlated with the severity of hearing loss（P<0.05）. Of the 22 EVA patients diagnosed by HRCT, 21 were positive for SLC26A4 gene mutation. The positive rate of EVA by SLC26A4 gene sequencing was highly consistent with HRCT（Kappa=0.975）. Conclusion:The size of MP and OP in EVA patients was related to the degree of hearing loss, but not to the stable nature of hearing loss. Temporal bone HRCT scanning and SLC26A4 gene sequencing are highly consistent in the diagnosis of EVA. The latter has no radiation and can be combined with hearing screening for early diagnosis of EVA.

SLC26A4 mutation in Pendred syndrome with hypokalemia: A case report

Rationale:Pendred syndrome is an autosomal recessive disorder characterized by sensorineural hearing loss, inner ear malformations, goiter, and abnormal organification of iodide. It is caused by mutations in SLC26A4 gene, which encodes pendrin (a transporter of chloride, bicarbonate, and iodide). Pendred syndrome is a common cause of syndromic deafness, but the metabolic abnormalities it causes are often overlooked. Here, we report the case of a patient diagnosed with Pendred syndrome with hypokalemia.Patient concerns:A 53-year-old deaf-mute woman was hospitalized due to severe limb asthenia. The emergency examination showed that her blood potassium level was 1.8 mmol/L.Diagnoses:Through the genetic test, we found a mutation of SLC26A4 gene in NM_000441: c.2027T>A, p.L676Q, as well as the SLC26A4 exon 5-6 deletion. These genetic variations pointed to Pendred syndrome (an autosomal recessive disorder that mainly affects the inner ear, thyroid, and kidney) which is a common cause of syndromic deafness.Interventions:The patient was treated with potassium supplements and screened for the cause of hypokalemia.Outcomes:The patient was discharged after her potassium levels rose to the normal range.Lessons:Patients with Pendred syndrome may also have certain metabolic abnormalities; thus, more attention should be paid to them during clinical diagnosis.

Compound heterozygous variants of the SLC26A4 gene in a Chinese family with enlarged vestibular aqueducts

BackgroundTo investigate the genetic causes of hearing loss in patients with enlarged vestibular aqueduct (EVA), the SLC26A4-related genotypes and phenotypes were analyzed. SLC26A4 gene is closely associated with EVA and its homozygous mutations or compound heterozygous mutations may cause deafness and strongly affect quality of life.MethodsThe patients who came to our hospital for hearing test and accompanied by bilateral hearing abnormalities were collected for fifteen deafness-related gene mutations detection. Those who are positive will be verified by Sanger sequencing, combined with family history, hearing test, and computerized tomography (CT) of the temporal bone, aiming to diagnose the enlarged vestibular aqueducts. Whole-exome sequencing were performed when necessary.ResultsOur patient failed hearing screening on both sides twice, and EVA (> 1.5 mm) was diagnosed by CT. This study has identified a novel missense mutation in the SLC26A4 gene, c.2069T>A, which in compound heterozygosity with c.1174A>T is likely to be the cause of hearing loss. The novel heterozygous c.2069T>A mutation of SLC26A4 gene has been submitted to Clinvar with Variation ID 1,048,780.ConclusionOur findings expand the gene mutation spectrum of SLC26A4 and provide additional knowledge for diagnosis and genetic counseling associated with EVA-induced hearing loss.