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Introduction: Tufting enteropathy is a rare cause of congenital diarrhea in neonates. It is characterized by the abnormal distribution of epithelial adhesion molecules, which causes enterocytes to shed into the lumen, forming the characteristic tufts. Case presentation: A 15-day-old female neonate was taken by her parents to the emergency department of a tertiary care hospital due to diarrheal stools she had been experiencing since birth. The patient presented with dehydration, abnormal weight loss, metabolic acidosis, and acute kidney failure. She received treatment with alizapride, loperamide, zinc sulfate, and probiotics, but after 75 days of treatment she was still symptomatic. An upper tract endoscopy and colonoscopy were performed, finding flattening of the villi and lymphoid cells in the lamina propria. However, the symptoms persisted, and she died at the age of ten months. A post-mortem exome sequencing reported tufting enteropathy. Conclusions. When congenital diarrhea is present, tufting enteropathy should be considered. An early molecular study would allow to evaluate the possibility of performing an intestinal transplant or modifying the treatment to meet the patient’s palliative care needs.

Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Congenital diarrhoeas and enteropathies (CODE) are a heterogeneous group of disorders. Many affected infants present with catastrophic dehydration in the first few days of life, although the clinical phenotype is variable. Advances in the understanding of underlying pathomechanisms and genetic testing, as well as improved management, in particular intravenous nutrition support, have allowed affected patients to survive well beyond childhood. Awareness and understanding of these rare diseases are hence needed, both amongst paediatricians and adult physicians. In this review, we discuss the different groups of disorders based on a review of the current literature and provide a diagnostic and therapeutic approach. Many of the subtypes of CODE result in the need for prolonged or indefinite parenteral nutrition. Further research is needed to identify new CODE to improve the recognition and management of these children, which can assist in developing new targeted therapies and potentially a long-term cure.

Congenital diarrhea and enteropathies (CODEs) constitute a group of rare genetic disorders characterized by severe diarrhea and malabsorption in the neonatal period or early infancy. Timely diagnosis and treatment is essential to prevent life-threatening complications, including dehydration, electrolyte imbalance, and malnutrition. This review offers a simplified approach to the diagnosis of CODEs, with a specific focus on microvillus inclusion disease (MVID), congenital tufting enteropathy (CTE), congenital chloride diarrhea (CLD), and congenital sodium diarrhea (CSD). Patients with CODEs typically present with severe watery or occasionally bloody diarrhea, steatorrhea, dehydration, poor growth, and developmental delay. Therefore, it is crucial to thoroughly evaluate infants with diarrhea to rule out infectious, allergic, or anatomical causes before considering CODEs as the underlying etiology. Diagnostic investigations for CODEs encompass various modalities, including stool tests, blood tests, immunological studies, endoscopy and biopsies for histology and electron microscopy, and next-generation sequencing (NGS). NGS plays a pivotal role in identifying the genetic mutations responsible for CODEs. Treatment options for CODEs are limited, often relying on total parenteral nutrition for hydration and nutritional support. In severe cases, intestinal transplantation may be considered. The long-term prognosis varies among specific CODEs, with some patients experiencing ongoing intestinal failure and associated complications. In conclusion, the early recognition and accurate diagnosis of CODEs are of paramount importance for implementing appropriate management strategies. Further research and advancements in genetic testing hold promise for enhancing diagnostic accuracy and exploring potential targeted therapies for these rare genetic disorders., (© 2023. Crown.)

Congenital chloride diarrhea (CCD) is a rare but significant genetic disorder characterized by severe electrolyte imbalances resulting from impaired intestinal chloride absorption. Affected children experience persistent diarrhea, dehydration, and malnutrition, complicating medical and developmental care. The enhancement of prenatal detection is crucial for improved patient management, early interventions, and informed genetic counseling. However, despite advancements in medicine, the complex nature and rarity of CCD make prenatal detection challenging. In this study, we report a fetal case where prenatal magnetic resonance imaging (MRI) effectively identified the distinctive characteristics of CCD, providing insights into the complexities of diagnosis and suggesting avenues for enhanced early detection strategies., (Sociedad Argentina de Pediatría.)

Background: Congenital sucrase-isomaltase deficiency (CSID) is a rare inherited carbohydrate malabsorption disorder caused by sucrase-isomaltase ( SI ) gene variants. In CSID, an autosomal recessively inherited disease, symptoms can also be seen in individuals with heterozygous mutations., Methods: The variant spectrum was evaluated retrospectively in individuals who presented with chronic diarrhea between 2014 and 2022 and had undergone genetic testing of the SI gene considering CSID due to diet-related complaints., Results: Ten patients with chronic diarrhea were genetically evaluated with SI gene sequencing. In patients diagnosed with CSID and whose symptoms improved with enzyme replacement therapy, the genetic mutation zygosity was found to be heterozygous at a rate of 90%. In 10% of the patients, the mutation was homozygous. Limiting consuming sucrose and isomaltose foods reduced the patients' complaints, but the symptoms did not disappear completely. With the initiation of sacrosidase enzyme replacement therapy, the patient's complaints completely disappeared., Conclusion: In CSID, defined as an autosomal recessive disease, clinical symptoms can also be seen in heterozygous cases previously described as carriers, and these patients also benefit from sacrosidase enzyme replacement therapy. In light of these findings, the autosomal recessive definition of CSID does not fully characterize the disease.What is Known:CSID is a rare inherited carbohydrate malabsorption disorder caused by sucrase-isomaltase gene variants.In congenital sucrase-isomaltase deficiency, an autosomal recessively inherited disorder, symptoms can also be seen in individuals with heterozygous mutations.What is new:Severe disease symptoms can also be seen in heterozygous cases, which were thought to be carriers because the disease was previously described as autosomal recessive.Sacrosidase enzyme replacement therapy also eliminates the disease symptoms in patients with heterozygous CSID mutations. This is the second study on sucrase-isomaltase enzyme deficiency pediatric groups in Türkiye and Europe.

Introduction: Congenital chloride diarrhoea (CCD) is an autosomal recessive condition that causes secretory diarrhoea and potentially deadly electrolyte imbalances in infants because of solute carrier family 26 member 3 (SLC26A3) gene mutations., Case Presentation: A 7-month-old Chinese infant with a history of maternal polyhydramnios presented with frequent watery diarrhoea, severe dehydration, hypokalaemia, hyponatraemia, failure to thrive, metabolic alkalosis, hyperreninaemia, and hyperaldosteronaemia. Genetic testing revealed a compound heterozygous SLC26A3 gene mutation in this patient (c.269_270dup and c.2006 C > A). Therapy was administered in the form of oral sodium and potassium chloride supplements, which decreased stool frequency., Conclusions: CCD should be considered when an infant presents with prolonged diarrhoea during infancy, particularly in the context of maternal polyhydramnios and dilated foetal bowel loops., (© 2024. The Author(s).)

Mutations in the Kunitz-type serine protease inhibitor HAI-2, encoded by SPINT2, are responsible for the pathogenesis of syndromic congenital sodium diarrhea (SCSD), an intractable secretory diarrhea of infancy. Some of the mutations cause defects in the functionally required Kunitz domain 1 and/or subcellular targeting signals. Almost all SCSD patients, however, harbor SPINT2 missense mutations that affect the functionally less important Kunitz domain 2. How theses single amino acid substitutions inactivate HAI-2 was, here, investigated by the doxycycline-inducible expression of three of these mutants in HAI-2-knockout Caco-2 human colorectal adenocarcinoma cells. Examining protein expressed from these HAI-2 mutants reveals that roughly 50% of the protein is synthesized as disulfide-linked oligomers that lose protease inhibitory activity due to the distortion of the Kunitz domains by disarrayed disulfide bonding. Although the remaining protein is synthesized as monomers, its glycosylation status suggests that the HAI-2 monomer remains in the immature, lightly glycosylated form, and is not converted to the heavily glycosylated mature form. Heavily glycosylated HAI-2 possesses full anti-protease activity and appropriate subcellular targeting signals, including the one embedded in the complex-type N-glycan. As predicted, these HAI-2 mutants cannot suppress the excessive prostasin proteolysis caused by HAI-2 deletion. The oligomerization and glycosylation defects have also been observed in a colorectal adenocarcinoma line that harbors one of these SPINT2 missense mutations. Our study reveals that the abnormal protein folding and N-glycosylation can cause widespread HAI-2 inactivation in SCSD patents., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Chronic diarrhea presents a significant challenge for managing nutritional and electrolyte deficiencies, especially in children, given the higher stakes of impacting growth and developmental consequence. Congenital secretory diarrhea (CSD) compounds this further, particularly in the case of the activating variants of the guanylate-cyclase 2C (GUCY2C) gene. GUCY2C encodes for the guanylate-cyclase 2C (GC-C) receptor that activates the downstream cystic fibrosis transmembrane receptor (CFTR) that primarily drives the severity of diarrhea with an unclear extent of influence on other intestinal channels. Thus far, management for CSD primarily consists of mitigating nutritional, electrolyte, and volume deficiencies with no known pathophysiology-driven treatments. For activating variants of GUCY2C, experimental compounds have shown efficacy in vitro for direct inhibition of GC-C but are not currently available for clinical use. However, Crofelemer, a CFTR inhibitory modulator with negligible systemic absorption, can theoretically help to treat this type of CSD. Herein, we describe and characterize the clinical course of a premature male infant with a de novo missense variant of GUCY2C not previously reported and highly consistent with CSD. With multi-disciplinary family-directed decision-making, a treatment for CSD was evaluated for the first time to our knowledge with Crofelemer., (© 2023 Wiley Periodicals LLC.)

Biallelic SPINT2 pathogenic variants cause a syndromic form of congenital diarrhea and enteropathy (OMIM 270420). To date, 35 patients have been reported and all presented with additional extra-intestinal features, apart from one case. We report on a 5-year-old girl who presented early in life with diarrhea and was found to have a novel homozygous variant in SPINT2. Pathological studies confirmed tufting enteropathy, and during her 5 years of life, she has not developed any extra-intestinal features. Molecular analysis detected a homozygous variant (NM_021102.4: c.203A>G (p. [Tyr68Cys]) in SPINT2. This is the first missense variant reported in the first Kunitz domain (KD1) of SPINT2 in humans. In vitro functional studies of this variant confirmed the deleterious effect leading to the loss of inhibitory activity of the intestinal serine proteases. This is the first description of SPINT2-related diarrhea in a patient who lived without long-term total parenteral nutrition. This study expands the clinical and molecular characteristics of SPINT2-related conditions., (© 2023 Wiley Periodicals LLC.)

Traumatic brain injury (TBI) involves an acute injury (primary damage), which may evolve in the hours to days after impact (secondary damage). Seizures and cortical spreading depolarization (CSD) are metabolically demanding processes that may worsen secondary brain injury. Metabolic stress has been associated with mitochondrial dysfunction, including impaired calcium homeostasis, reduced ATP production, and elevated ROS production. However, the association between mitochondrial impairment and vascular function after TBI is poorly understood. Here, we explored this association using a rodent closed head injury model. CSD is associated with neurobehavioral decline after TBI. Craniotomy was performed to elicit CSD via electrical stimulation or to induce seizures via 4-aminopyridine application. We measured vascular dysfunction following CSDs and seizures in TBI animals using laser doppler flowmetry. We observed a more profound reduction in local cortical blood flow in TBI animals compared to healthy controls. CSD resulted in mitochondrial dysfunction and pathological signs of increased oxidative stress adjacent to the vasculature. We explored these findings further using electron microscopy and found that TBI and CSDs resulted in vascular morphological changes and mitochondrial cristae damage in astrocytes, pericytes and endothelial cells. Overall, we provide evidence that CSDs induce mitochondrial dysfunction, impaired cortical blood flow, and neurobehavioral deficits in the setting of TBI., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Congenital sodium diarrhea (CSD) is a rare disorder causing electrolyte imbalances due to excessive diarrhea. In pediatric literature, common practice for treating CSD includes parenteral nutrition (PN) for fluid, nutrient, and electrolyte support through the first year of the patient's life. The aim of this study was to report a neonate who showed common symptoms of CSD, including a distended abdomen, large amounts of clear, yellow fluid draining from the rectum, dehydration, and electrolyte abnormalities., Case Summary: A diagnostic gene panel was completed and confirmed heterozygous variant GUCY2C gene associated with autosomal dominant CSD. The infant was initially treated with PN to maintain fluid, nutrient, and electrolyte status, but was subsequently transitioned to full enteral feeds, showing improvement in symptoms. Frequent therapy adjustments were required to maintain appropriate electrolyte levels during the duration of the hospital stay. At discharge, the infant followed an enteral fluid maintenance plan that provided symptomatic control through the first year of life., Conclusion: This case demonstrated the ability to maintain electrolyte levels in a patient through enteral means while avoiding long-term use of intravenous access., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Cesarean scar disorder (CSD) is an entity recently defined as uterine niche with at least one primary or 2 secondary symptoms. CSDs can be visualized by hysterosalpingography, transvaginal sonography, saline infusion sonohysterography, hysteroscopy, and magnetic resonance imaging, but diagnosis should be performed by exams able to measure the residual myometrial thickness (RMT). Although there is a limited number of studies evaluating fertility and reproductive outcomes after different types of surgery, the following consideration should be kept in mind. Asymptomatic women should not be operated with the hope of improving obstetrical outcomes. It is reasonable to consider hormone therapy for CSDs as a symptomatic treatment in women who no longer wish to conceive and have no contraindications. In case of failure of or contraindications to medical treatment, surgery should be offered according to the severity of symptoms, including infertility, the desire or otherwise to preserve the uterus, the size of the CSD, and RMT measurement. Hysteroscopy is considered to be more of a resection than a repair, so women who desire pregnancy should be excluded from this technique in case of RMT <3 mm. In this instance, repair is essential and can only be achieved by a laparoscopic or vaginal approach. The benefit of laparoscopic approach seems to persist after subsequent CS. Women with CSDs need to be given complete information, including available literature, before any treatment decision is made., Competing Interests: Declaration of competing interest The authors have no conflicts of interest. O.D. has nothing to disclose., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A male infant with prenatal history significant for polyhydramnios requiring multiple amnioreductions with suspicion of small bowel atresia was born at 31 weeks 5 days' gestation with abdominal distension. He underwent three exploratory laparotomies and ileostomy for small bowel obstruction and was found to have fluid-filled intestinal dilatation. Serum and stool chemistries suggested sodium secretory diarrhoea. A rapid whole-exome sequencing confirmed de novo guanylate cyclase mutation variant as a cause for his congenital sodium secretory diarrhoea. He required large volume of fluid and electrolyte replacement along with total parenteral nutrition. Several medications to restore normal sodium homeostasis by targeting molecular mechanisms and pathogenesis described in previous literature failed to decrease stool output and electrolyte loss. He was discharged home at 11 months of age on total parenteral nutrition and weekly iron therapy., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Context: Biallelic pathogenic variants in the NEUROG3 gene cause malabsorptive diarrhea, insulin-dependent diabetes mellitus (IDDM), and rarely hypogonadotropic hypogonadism. With only 17 reported cases, the clinical and mutational spectra of this disease are far from complete., Objective: To identify the underlying genetic etiology in 3 unrelated Thai patients who presented with early-onset malabsorptive diarrhea, endocrine abnormalities, and renal defects and to determine the pathogenicity of the newly identified pathogenic variants using luciferase reporter assays and western blot., Methods: Three unrelated patients with congenital diarrhea were recruited. Detailed clinical and endocrinological features were obtained. Exome sequencing was performed to identify mutations and in vitro functional experiments including luciferase reporter assay were studied to validate their pathogenicity., Results: In addition to malabsorptive diarrhea due to enteric anendocrinosis, IDDM, short stature, and delayed puberty, our patients also exhibited pituitary gland hypoplasia with multiple pituitary hormone deficiencies (Patient 1, 2, 3) and proximal renal tubulopathy (Patient 2, 3) that have not previously reported. Exome sequencing revealed that Patient 1 was homozygous for c.371C > G (p.Thr124Arg) while the other 2 patients were homozygous for c.284G > C (p.Arg95Pro) in NEUROG3. Both variants have never been previously reported. Luciferase reporter assay demonstrated that these 2 variants impaired transcriptional activity of NEUROG3., Conclusions: This study reported pituitary gland hypoplasia with multiple pituitary hormone deficiencies and proximal renal tubulopathy and 2 newly identified NEUROG3 loss-of-function variants in the patients with NEUROG3-associated syndrome., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Congenital sodium diarrhea (CSD) is a rare enteropathy displaying both broad variability in clinical severity and genetic locus and allelic heterogeneity. Eleven CSD patients were reported so far with SLC9A3 variants that impair the function of the encoded intestinal sodium-proton exchanger 3 (NHE3)., Methods: We report a 4-year-old patient, born prematurely in the 35th week of gestation, with antenatal polyhydramnios and dilated intestinal loops, and with diarrhea of congenital onset, 2-6 times a day, and with polydipsia. She thrived age-appropriately under a normal family diet. Serum sodium levels were repeatedly normal but urinary sodium excretion was low. Exome sequencing revealed compound heterozygous variants in SLC9A3 as the likely cause of the congenital diarrhea., Results: While exome sequencing did not reveal pathogenic or likely pathogenic variants in other genes that cause syndromic or non-syndromic forms of congenital and intractable diarrheas, we identified novel compound heterozygous variants in SLC9A3, a complex allele with two missense changes, NP&#95;004165.2:p.[Ser331Leu;Val449Ile] and in-trans the missense variant p.(Phe451Ser)., Conclusion: The clinical phenotype here appears to localize to the milder end of the known CSD spectrum, and the identified variants suggest that this is the twelfth patient reported to date with CSD due to mutations in SLC9A3., (© 2022 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

BACKGROUND Congenital chloride diarrhea (CCD) is an autosomal recessive disease that is usually diagnosed in early childhood. Mutations in the SLC26A3 gene have been attributed to the primary etiology of disease development. Patients with CCD usually present with electrolyte disturbances, metabolic alkalosis, and chronic diarrhea. Early diagnosis is essential to prevent long-term complications that often require genetic testing. Bartter syndrome is another congenital disorder that has clinical features similar to CCD, which might cause a delay in diagnosis in a few patients. CASE REPORT We describe the case of a 28-year-old man who was misdiagnosed as having Bartter syndrome when he was 5 months old based on the clinical features of hypokalemia, metabolic alkalosis, and a family history of Bartter syndrome. He had multiple admissions with diarrhea and was diagnosed with ulcerative colitis. Unfortunately, the course was complicated by renal failure, and the patient underwent a kidney transplant. Persistent metabolic alkalosis with diarrhea after transplantation was unusual in Bartter syndrome. Therefore, his primary diagnosis was challenged and suspicion of CCD was raised, which was confirmed by genetic testing. CONCLUSIONS CCD is a rare congenital disorder that requires high clinical suspicion and often a genetic test to confirm diagnosis. Here, we report a patient who was misdiagnosed as having Bartter syndrome until early adulthood owing to several misleading factors. We hope by reporting this case it will raise awareness about CCD in high-prevalence areas and the importance of early diagnosis to prevent serious complications.

Background and Aims: Subjects with congenital chloride diarrhea (CLD; a defect in solute carrier family 26 member 3 (SLC26A3)) are prone to inflammatory bowel disease (IBD). We investigated fecal microbiota in CLD and CLD-associated IBD. We also tested whether microbiota is modulated by supplementation with the short-chain fatty acid butyrate., Subjects and Methods: We recruited 30 patients with CLD for an observational 3-week follow-up study. Thereafter, 16 consented to oral butyrate substitution for a 3-week observational period. Fecal samples, collected once a week, were assayed for calprotectin and potential markers of inflammation, and studied by 16S ribosomal ribonucleic acid (rRNA) gene amplicon sequencing and compared to that of 19 healthy controls and 43 controls with Crohn's disease. Data on intestinal symptoms, diet and quality of life were collected., Results: Patients with CLD had increased abundances of Proteobacteria, Veillonella, and Prevotella, and lower abundances of normally dominant taxa Ruminococcaceae and Lachnospiraceae when compared with healthy controls and Crohn´s disease. No major differences in fecal microbiota were found between CLD and CLD-associated IBD (including two with yet untreated IBD). Butyrate was poorly tolerated and showed no major effects on fecal microbiota or biomarkers in CLD., Conclusions: Fecal microbiota in CLD is different from that of healthy subjects or Crohn´s disease. Unexpectedly, no changes in the microbiota or fecal markers characterized CLD-associated IBD, an entity with high frequency among patients with CLD., Competing Interests: KLK has received consultancy fees from Abbvie, Biocodex and Tillotts Pharma. This does not alter our adherence to PLOS ONE policies on sharing data and materials. Other authors declare no potential conflicts of interest.

Congenital chloride losing diarrhoea (CCLD) is a rare disease caused by mutations in an intestinal chloride/bicarbonate ion exchange channel. Few reports describe CCLD in adults and none has described the impact of a parasitic infection on CCLD. Severe diarrhoea may result in hypokalaemia with QT interval prolongation. Treatment with antiemetics may further increase the QT interval. To raise awareness of this preventable complication, we describe the course of a woman in her 20s with CCLD who developed COVID-19 and a Blastocystis hominis infestation. Treatment with antiemetics and hypokalaemia resulted in prolongation of the QT interval to 640 ms. While, the QT interval normalised with discontinuation of antiemetics and electrolyte replacement, patients with CCLD must take precautions to prevent gastrointestinal infections. Regardless, whenever patients with CCLD present to hospital, the authors recommend monitoring the QT interval and avoiding medications that predispose to torsade de pointes., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Background & Aims: UNC45A is a myosin (co-)chaperone, and mutations in the UNC45A gene were recently identified in osteo-oto-hepato-enteric (O2HE) syndrome patients presenting with congenital diarrhea and intrahepatic cholestasis. Congenital diarrhea and intrahepatic cholestasis are also the prime symptoms in patients with microvillus inclusion disease (MVID) and mutations in MYO5B, encoding the recycling endosome-associated myosin Vb. The aim of this study was to determine whether UNC45A and myosin Vb are functionally linked., Methods: CRISPR-Cas9 gene editing and site-directed mutagenesis were performed with intestinal epithelial and hepatocellular cell lines, followed by Western blotting, quantitative polymerase chain reaction, and scanning electron and/or confocal fluorescence microscopy to determine the relationship between (mutants of) UNC45A and myosin Vb., Results: UNC45A depletion in intestinal and hepatic cells reduced myosin Vb protein expression, and in intestinal epithelial cells, it affected 2 myosin Vb-dependent processes that underlie MVID pathogenesis: rat sarcoma-associated binding protein (RAB)11A-positve recycling endosome positioning and microvilli development. Reintroduction of UNC45A in UNC45A-depleted cells restored myosin Vb expression, and reintroduction of UNC45A or myosin Vb, but not the O2HE patient UNC45A-c.1268T>A variant, restored recycling endosome positioning and microvilli development. The O2HE patient-associated p.V423D substitution, encoded by the UNC45A-c.1268T>A variant, impaired UNC45A protein stability but as such not the ability of UNC45A to promote myosin Vb expression and microvilli development., Conclusions: A functional relationship exists between UNC45A and myosin Vb, thereby connecting 2 rare congenital diseases with overlapping enteropathy at the molecular level. Protein instability rather than functional impairment underlies the pathogenicity of the O2HE syndrome-associated UNC45A-p.V423D mutation., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Gain-of-function mutations in guanylyl cyclase C (GCC) result in persistent diarrhea with perinatal onset. We investigated a specific GCC inhibitor, SSP2518, for its potential to treat this disorder., Methods: We investigated the effect of SSP2518 on GCC-mediated intracellular cyclic guanosine monophosphate (cGMP) levels and on GCC-mediated chloride secretion in intestinal organoids from 3 patients with distinct activating GCC mutations and from controls, with and without stimulation of GCC with heat-stable enterotoxin., Results: Patient-derived organoids had significantly higher basal cGMP levels than control organoids, which were lowered by SSP2518 to levels found in control organoids. In addition, SSP2518 significantly reduced cGMP levels and chloride secretion in patient-derived and control organoids (P < 0.05 for all comparisons) after heat-stable enterotoxin stimulation., Discussion: We reported in this study that the GCC inhibitor SSP2518 normalizes cGMP levels in intestinal organoids derived from patients with GCC gain-of-function mutations and markedly reduces cystic fibrosis transmembrane conductance regulator-dependent chloride secretion, the driver of persistent diarrhea., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology.)

Background: Congenital chloride diarrhoea [CLD] is a rare autosomal recessive disease caused by mutations in the solute family carrier 26 member 3 [SLC26A3] gene. Patients suffer from life-long watery diarrhoea and chloride loss. Inflammatory bowel disease [IBD] has been reported in individual patients with CLD and in scl26a3-deficient mice., Methods: We performed an international multicentre analysis to build a CLD cohort and to identify cases with IBD. We assessed clinical and genetic characteristics of subjects and studied the cumulative incidence of CLD-associated IBD., Results: In a cohort of 72 patients with CLD caused by 17 different SLC26A3 mutations, we identified 12 patients [17%] diagnosed with IBD. Nine patients had Crohn's disease, two ulcerative colitis and one IBD-unclassified [IBD-U]. The prevalence of IBD in our cohort of CLD was higher than the highest prevalence of IBD in Europe [p < 0.0001]. The age of onset was variable [13.5 years, interquartile range: 8.5-23.5 years]. Patients with CLD and IBD had lower z-score for height than those without IBD. Four of 12 patients had required surgery [ileostomy formation n = 2, ileocaecal resection due to ileocaecal valve stenosis n = 1 and colectomy due to stage II transverse colon cancer n = 1]. At last follow-up, 5/12 were on biologics [adalimumab, infliximab or vedolizumab], 5/12 on immunosuppressants [azathioprine or mercaptopurine], one on 5-ASA and one off-treatment., Conclusions: A substantial proportion of patients with CLD develop IBD. This suggests the potential involvement of SL26A3-mediated anion transport in IBD pathogenesis. Patients with CLD-associated IBD may require surgery for treatment failure or colon cancer., (© The Author(s) 2021. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Introduction: Congenital chloride diarrhea (CLD) is a rare autosomal recessive disorder characterized by watery diarrhea with a high level of fecal Cl - , metabolic alkalosis, and electrolyte alterations. Several intestinal and extraintestinal complications and even death can occur. An optimal knowledge of the clinical features and best therapeutic strategies is mandatory for an effective management., Methods: Articles published between 1 January 1965 and 31 December 2019, reported in PUBMED and EMBASE, were evaluated for a systematic review analyzing four categories: anamnestic features, clinical features, management, and follow-up strategies., Results: Fifty-seven papers reporting information on 193 CLD patients were included. The most common anamnestic features were positive family anamnesis for chronic diarrhea (44.4%), consanguinity (75%), polyhydramnios (98.3%), preterm delivery (78.6%), and failure to pass meconium (60.7%). Mean age at diarrhea onset was 6.63 days. Median diagnostic delay was 60 days. Prenatal diagnosis, based on molecular analysis, was described in 40/172 (23.3%). All patients received NaCl/KCl-substitutive therapy. An improvement of diarrhea during adulthood was reported in 91.3% of cases. Failure to thrive (21.6%) and chronic kidney disease (17.7%) were the most common complications., Conclusions: This analysis of a large population suggests the necessity of better strategies for the management of CLD. A close follow-up and a multidisciplinary approach is mandatory to manage this condition characterized by heterogeneous and multisystemic complications., Impact: In this systematic review, we describe data regarding anamnestic features, clinical features, management, and follow-up of CLD patients obtained from the largest population of patients ever described to date. The results of our investigation could provide useful insights for the diagnostic approach and the management of this condition., (© 2020. International Pediatric Research Foundation, Inc.)

Background: The main symptoms of congenital chloride diarrhea (CCD) main symptoms are watery diarrhea, hypochloremia, and hypokalemic metabolic alkalosis. Silver-Russell syndrome (SRS) is a heterogeneous imprinting disorder characterized by severe intrauterine retardation, poor postnatal growth, and facial dysmorphism., Methods: Parent-offspring trio whole-exome sequencing was used to identify the causal variants. Sequencing reads were mapped to the reference of human genome version hg19. Sanger sequencing was performed as a confirmatory experiment., Results: The proband was a patient with SRS caused by maternal uniparental disomy 7. The CCD of the proband was caused by homozygous variant c.1515-1 (IVS13) G>A; both mutated alleles were inherited from her mother., Conclusion: We report the first clinical case of CCD and SRS occurring together. Patients with milder phenotypes may be difficult to diagnose in early stage, but close monitoring of potential complications is important for identification., (© 2021 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.)

Proprotein convertase 1/3 (PC1/3), encoded by the PCSK1 gene, is expressed in neuronal and (entero)endocrine cell types, where it cleaves and hence activates a number of protein precursors that play a key role in energy homeostasis. Loss-of-function mutations in PCSK1 cause a recessive complex endocrinopathy characterized by malabsorptive diarrhea and early-onset obesity. Despite the fact that neonatal malabsorptive diarrhea is observed in all patients, it has remained understudied. The aim of this study was to investigate the enteroendocrine pathologies in a male patient with congenital PCSK1 deficiency carrying the novel homozygous c.1034A>C (p.E345A) mutation. This patient developed malabsorptive diarrhea and metabolic acidosis within the first week of life, but rapid weight gain was observed after total parenteral nutrition, and he displayed high proinsulin levels and low adrenocorticotropin. In vitro analysis showed that the p.E345A mutation in PC1/3 resulted in a (near) normal autocatalytic proPC1/3 processing and only partially impaired PC1/3 secretion, but the processing of a substrate in trans was completely blocked. Immunohistochemical staining did not reveal changes in the proGIP/GIP and proglucagon/GLP-1 ratio in colonic tissue. Hence, we report a novel PCSK1 deficient patient who, despite neonatal malabsorptive diarrhea, showed a normal morphology in the small intestine.

A 5-year-old girl presented with treatment-refractory dry eye and recurrent episodes of eye pain. She had been previously diagnosed with syndromic congenital sodium diarrhea (SCSD) caused by a pathogenic variant in SPINT2. Her local pediatric ophthalmologist had made the diagnosis of severe dry eye with corneal erosions, based on which, we arranged an eye exam under anesthesia (EUA) and punctal plug placement. Anterior segment optical coherence tomography (OCT) and corneal photographs were taken during the procedure. There are reports describing similar ophthalmic findings in this syndrome. However, to the best of our knowledge, this is the first case report to document OCT imaging and corneal photographs in a patient with SCSD, which we feel expands the ophthalmic phenotype of this rare genetic disorder., (© 2021 Wiley Periodicals LLC.)

Context: Mitchell-Riley syndrome due to RFX6 gene mutations is characterized by neonatal diabetes and protracted diarrhea. The RFX6 gene encodes a transcription factor involved in enteroendocrine cell differentiation required for beta-cell maturation. In contrast to the pathway by which RFX6 mutations leads to diabetes, the mechanisms underlying protracted diarrhea are unknown., Objective: To assess whether glucagon-like peptide-1 (GLP-1) was involved in the pathogenesis of Mitchell-Riley syndrome protracted diarrhea., Methods: Two case report descriptions. in a tertiary pediatric hospital. "Off-label" treatment with liraglutide. We describe 2 children diagnosed with Mitchell-Riley syndrome, presenting neonatal diabetes and protracted diarrhea. Both patients had nearly undetectable GLP-1 plasma levels and absence of GLP-1 immunostaining in distal intestine and rectum. The main outcome was to evaluate whether GLP-1 analogue therapy could improve Mitchell-Riley syndrome protracted diarrhea., Results: "Off-label" liraglutide treatment, licensed for type 2 diabetes treatment in children, was started as rescue therapy for protracted intractable diarrhea resulting in rapid improvement during the course of 12 months., Conclusion: Congenital GLP-1 deficiency was identified in patients with Mitchell-Riley syndrome. The favorable response to liraglutide further supports GLP-1 involvement in the pathogenesis of protracted diarrhea and its potential therapeutic use., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: Congenital diarrheal disorders (CDDs) are a group of rare diseases among which some present as inherited disorders of intestinal electrolyte transportation: congenital chloride diarrhea (CCD) and congenital sodium diarrhea (CSD) with prenatal manifestations, mainly polyhydramnios, leading to premature delivery. Affected neonates present with watery stools, sometimes mistaken as urine, leading to a misdiagnosis of Bartter syndrome. The aim of this study was to study the value of a prenatal biochemical pattern in the case of suspected CDD., Methods: We retrospectively studied 12 amniotic fluids of CDD-affected fetuses prenatally suspected and confirmed after birth. Digestive enzymes, proteins, and electrolytes were assayed and showed abnormal biochemical patterns., Results: The 12 infants (eight CCD- and four CSD-affected) were born prematurely with a normal birth weight. Electrolytes and the Bartter index were normal for all cases. Amniotic fluid enzyme patterns were abnormal: anal leakage for nine, as expected, but vomiting of bile was observed for three infants, for whom an occlusive syndrome required surgery, and thereafter severe complications appeared with a poor prognosis., Conclusion: Amniotic fluid biochemical patterns differentiate CDD from Bartter syndrome. If a vomiting bile pattern is observed, postnatal management should take into account the hypothesis of a most severe complication., (© 2020 John Wiley & Sons Ltd.)

Introduction: To analyze the clinical features and SLC26A3 mutation of one patient in our hospital who had congenital loss of chlorine diarrhea (CLD), and to investigate the treatment of the disease and the prognosis., Material and Methods: By reviewing the literature, analyzing the clinical features and differential diagnosis and investigating the treatment and prognosis, the patient was diagnosed as CLD., Results: Excessive accumulation of amniotic fluid was observed during pregnancy. The patient was born prematurely with normal body weight. The patient was a 4-month old boy admitted for anorexia, watery diarrhea, electrolyte disorders (hyponatremia, hypokalemia and hypochloremia) and metabolic alkalosis. The patient was also considered to be affected by Batter syndrome. After treating with spironolactone, indomethacin and potassium chloride sustained release tablet, the symptom of watery diarrhea was alleviated, the ingested amount of milk increased gradually and the amount of urine became normal; however, electrolyte imbalance persisted and the frequency of bowel movements remained high. Genetic analysis demonstrated that the patient had a SLC26A3 c.269&#95;270dupAA homozygous mutation in exon 3, leading to a frameshift from 91st amino acid Gly and alteration of the SLC26A3 transmembrane protein sequence, thus resulting in a Cl-/HCO3- exchange barrier. The parents of the patient had normal phenotypes and were all heterozygous carriers of the mutation. Moreover, the patient was diagnosed as CLD. Sodium chloride and potassium chloride rather than spironolactone and indomenthacin were given to the patient to correct the dehydration, so the symptom of watery diarrhea alleviated and the blood gas and electrolyte levels returned to the normal range. In addition, the patients morale was good and the ingested amount of milk was moderate., Conclusions: Persistent diarrhea and electrolyte disorder in pediatrics are easy to misdiagnose as CLD. Furthermore, it is difficult to identify Batter syndrome, Gitelman syndrome, renal tubular acidosis and CLD. Blood and stool electrolyte detection and SLC26A3 genetic tests are helpful for diagnosis, and sodium chloride and potassium chloride replacement therapy are critical for the patient prognosis.

Purpose: To report the presence of drusen in infancy, in a patient with Type 1 retinopathy of prematurity and a rare congenital sodium diarrhea secondary to a sporadic GUCY2C mutation., Methods: A case report generated by review of clinical course, with imaging of 1 patient and literature review., Results: A 1.075-kg infant born at gestation age 27 weeks was admitted to our institution with respiratory distress and secretory diarrhea. During screening for retinopathy of prematurity, peripheral drusen-like subretinal deposits were identified. There were no similar findings in either parent or family history of ocular pathologies. Their distribution is atypical for that seen in other causes of early onset drusen such as autosomal dominant drusen or Sorsby fundus dystrophy. Retinopathy of prematurity was identified, which progressed to Type 1, and was treated with bilateral indirect peripheral retinal photocoagulation at gestational age of 40 weeks. Fluorescein angiography was performed and was consistent with peripheral drusen. Optical coherence tomography of the central macula and an awake electroretinogram at 6 months were normal. Serial examinations confirmed no progression in the drusen-like deposits or in retinopathy of prematurity, with clinically appropriate visual development observed during close follow-up., Conclusion: We identify a unique ocular phenotype of retinal drusen-like deposits in an infant with a rare, sporadic GUCY2C mutation.

Hyaline fibromatosis syndrome (HFS), resulting from ANTXR2 mutations, is an ultra-rare disease that causes intestinal lymphangiectasia and protein-losing enteropathy (PLE). The mechanisms leading to the gastrointestinal phenotype in these patients are not well defined. We present two patients with congenital diarrhea, severe PLE and unique clinical features resulting from deleterious ANTXR2 mutations. Intestinal organoids were generated from one of the patients, along with CRISPR-Cas9 ANTXR2 knockout, and compared with organoids from two healthy controls. The ANTXR2-deficient organoids displayed normal growth and polarity, compared to controls. Using an anthrax-toxin assay we showed that the c.155C>T mutation causes loss-of-function of ANTXR2 protein. An intrinsic defect of monolayer formation in patient-derived or ANTXR2 KO organoids was not apparent, suggesting normal epithelial function. However, electron microscopy and second harmonic generation imaging showed abnormal collagen deposition in duodenal samples of these patients. Specifically, collagen VI, which is known to bind ANTXR2, was highly expressed in the duodenum of these patients. In conclusion, despite resistance to anthrax-toxin, epithelial cell function, and specifically monolayer formation, is intact in patients with HFS. Nevertheless, loss of ANTXR2-mediated signaling leads to collagen VI accumulation in the duodenum and abnormal extracellular matrix composition, which likely plays a role in development of PLE.

Background: Congenital chloride diarrhea (CCD) is characterized by persistent chloride (Cl)-rich diarrhea evident from birth. CCD is a rare autosomal recessive disorder caused by defects in the solute carrier family 26 member 3 (SLC26A3) gene, which encodes an intestinal Cl - /HCO3 - , Na + -independent exchanger. Various mutations of SLC26A3 have been described in CCD. However, no de novo mutations have been found to be responsible for CCD. Here we report the first such occurrence., Methods: Clinical and laboratory findings during the perinatal period were obtained retrospectively from medical records. Mutations involving SLC26A3 were detected by Sanger sequencing., Results: The male infant reported here was delivered at 29 weeks of gestation. Just after birth, he had watery diarrhea without meconium passage. High chloride concentrations in the diarrhea led to a diagnosis of CCD. Direct sequencing of all coding exons in SLC26A3 including exon-intron boundaries disclosed 2 compound heterozygous mutations: c.382G>A, p.G128S and c.2063-1g>t. The c. 2063-1g>t mutation was confirmed in his mother's DNA, but c.382G>A, p.G128S was absent in both mother and father., Conclusion: We concluded that c.382G>A, p.G128S represented a de novo mutation of SLC26A3, a very rare event in autosomal recessive disorders. To our knowledge, this is the first CCD case involving a de novo novel mutation of SLC26A3., (© 2020 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

Congenital diarrhea and enteropathies (CODEs) are a group of monogenic disorders that often present with severe diarrhea in the first weeks of life. Enteric anendocrinosis (EA), an extremely rare cause of CODE, is characterized by a marked reduction of intestinal enteroendocrine cells (EC). EA is associated with recessively inherited variants in Neurogenin-3 (NEUROG3) gene. Here we investigate a case of a male infant who presented with mysterious severe malabsorptive diarrhea since birth. Thorough clinical assessments and laboratory tests were successful to exclude the majority of differential diagnosis categories. However, the patient's diagnosis was not established until the genetic test using whole-exome sequencing (WES) was performed. We identified a novel homozygous missense disease-causing variant (DCV) in NEUROG3 (c.413C>G, p.Thr138Arg). Moreover, molecular dynamic simulation analysis showed that (p.Thr138Arg) led to a global change of the NEUROG3 orientation affecting its DNA binding capacity. To the best of our knowledge, this is the first time to apply WES to reach a differential diagnosis of patients with CODEs. Our study not only expands our knowledge about NEUROG3 variants and their clinical consequences but also proves that WES is a very effective tool for the diagnosis of CODEs. This might be of value in early diagnosis of diseases and prenatal CODEs detection., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

The sodium-hydrogen exchanger isoform 3 (NHE3, SLC9A3) is abundantly expressed in the gastrointestinal tract and is proposed to play essential roles in Na+ and fluid absorption as well as acid-base homeostasis. Mutations in the SLC9A3 gene can cause congenital sodium diarrhea (CSD). However, understanding the precise role of intestinal NHE3 has been severely hampered due to the lack of a suitable animal model. To navigate this problem and better understand the role of intestinal NHE3, we generated a tamoxifen-inducible intestinal epithelial cell-specific NHE3 knockout mouse model (NHE3IEC-KO). Before tamoxifen administration, the phenotype and blood parameters of NHE3IEC-KO were unremarkable compared with control mice. After tamoxifen administration, NHE3IEC-KO mice have undetectable levels of NHE3 in the intestine. NHE3IEC-KO mice develop watery, alkaline diarrhea in combination with a swollen small intestine, cecum and colon. The persistent diarrhea results in higher fluid intake. After 3 weeks, NHE3IEC-KO mice show a ∼25% mortality rate. The contribution of intestinal NHE3 to acid-base and Na+ homeostasis under normal conditions becomes evident in NHE3IEC-KO mice that have metabolic acidosis, lower blood bicarbonate levels, hyponatremia and hyperkalemia associated with drastically elevated plasma aldosterone levels. These results demonstrate that intestinal NHE3 has a significant contribution to acid-base, Na+ and volume homeostasis, and lack of intestinal NHE3 has consequences on intestinal structural integrity. This mouse model mimics and explains the phenotype of individuals with CSD carrying SLC9A3 mutations., (© 2020 The Author(s).)

Background: Congenital chloride diarrhea (CLD; OMIM 214700) is a rare autosomal recessive disorder caused by pathogenic variations in the solute carrier family 26 member A3 (SLC26A3) gene. Without salt substitution, this chronic diarrheal disorder causes severe dehydration and electrolyte disturbances. Homozygous variants in the nearby gene SLC26A4 disrupt anion exchange in the inner ear and the thyroid, causing Pendred syndrome (PDS; OMIM 274600), which is the most frequent form of syndromic deafness., Case Presentation: We report an unusual co-occurrence of two rare homozygous mutations in both the SLC26A3 and SLC26A4 genes, causing a rare combination of both CLD and PDS in two siblings. Although the clinical pictures were typical, the combined loss of these anion transporters might modulate the risk of renal injury associated with CLD., Conclusions: Familial presentation of two rare autosomal recessive disorders with loss of function of different SLC26 anion transporters is described. Independent homozygous variants in the SLC26A3 and SLC26A4 genes cause CLD and PDS in siblings, shedding light on co-occurrence of rare recessive traits in the progeny of consanguineous couples.

Loss-of-function mutations in the nonconventional myosin Vb (Myo5b) result in microvillus inclusion disease (MVID) and massive secretory diarrhea that often begins at birth. Myo5b mutations disrupt the apical recycling endosome (ARE) and membrane traffic, resulting in reduced surface expression of apical membrane proteins. ARE disruption also results in constitutive phosphoinositide-dependent kinase 1 gain of function. In MVID, decreased surface expression of apical anion channels involved in Cl - extrusion, such as cystic fibrosis transmembrane conductance regulator (CFTR), should reduce fluid secretion into the intestinal lumen. But the opposite phenotype is observed. To explain this contradiction and the onset of diarrhea, we hypothesized that signaling effects downstream from Myo5b loss of function synergize with higher levels of glucocorticoids to activate PKA and CFTR. Data from intestinal cell lines, human MVID, and Myo5b KO mouse intestine revealed changes in the subcellular redistribution of PKA activity to the apical pole, increased CFTR phosphorylation, and establishment of apical cAMP gradients in Myo5b-defective cells exposed to physiological levels of glucocorticoids. These cells also displayed net secretory fluid fluxes and transepithelial currents mainly from PKA-dependent Cl - secretion. We conclude that Myo5b defects result in PKA stimulation that activates residual channels on the surface when intestinal epithelia are exposed to glucocorticoids at birth.

Congenital chloride diarrhoea is one of the rare causes of diarrhoea during infancy and it is infrequently reported throughout the world. It is an autosomal recessive condition which is more prevalent in Poland, Finland, Saudi Arabia and Kuwait while rarely reported in Pakistan. Our patient was 7.5-month-old baby boy who presented with diarrhoea since neonatal period. He had consanguineous parents. On examination, baby had distended abdomen, hypotonia and hyporeflexia. Investigations revealed hypochloremic hypokalemic metabolic alkalosis. Urinary electrolytes were normal. Stool electrolytes revealed increased stool chloride excretion that confirmed our diagnosis of congenital chloride diarrhoea. Patient was treated with intravenous fluids and electrolyte replacement, followed by oral potassium and sodium replacement. He was also started on butyrate, cholestyramine and proton-pump inhibitors. He started gaining weight during his hospital admission and is being followed up in clinic., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: To establish a congenital chloride diarrhea (CCD)-associated SLC26A3 c.392C>G (p.P131R) polymorphism-expressing cell model, and to investigate its biological function., Methods: The sequence of the SLC26A3 gene in GenBank was used to design the upstream and downstream single-guide RNA (sgRNA) that could specifically recognize the 392 locus of the SLC26A3 gene, and the sgRNA was mixed with the pSpCas9-puro vector after enzyme digestion to construct an eukaryotic recombinant expression plasmid (pSpCas9-SLC26A3). Caco-2 cells were transfected with the recombinant plasmid and synthesized single-stranded DNA oligonucleotides (ssODNs), and Taqman genotyping assay and Sanger sequencing were used to identify the expression of SLC26A3 c.392C>G (p.P131R) in Caco-2 cells. Wild-type Caco-2 cells were selected as normal control group and the Caco-2 cells with successful expression of SLC26A3 c.392C>G (p.P131R) was selected as P131R group. Both groups were treated with 100 ng/mL tumor necrosis factor-α (TNF-α), and then the normal control group was named as TNF-α group, and the P131R group was named as TNF-α+P131R group. Electric cell-substrate impedance sensing (ECIS) assay was used to evaluate the change in the monolayer barrier function of intestinal epithelial cells in the above four groups, and Western blot was used to measure the change in the expression of SLC26A3 protein in the normal control group and the P131R group., Results: The eukaryotic recombinant expression plasmid (pSpCas9-SLC26A3) was successfully constructed. Both Taqman genotyping assay and Sanger sequencing confirmed the successful establishment of the Caco-2 cell model of SLC26A3 c.392C>G (p.P131R) expression. ECIS assay showed that compared with the normal control group, the P131R group had a significant increase in the monolayer permeability of intestinal epithelial cells (P<0.05), and at the same time, the P131R group had a significantly greater increase in cell membrane permeability after the induction with 100 ng/mL TNF-α (P<0.05). Western blot showed that compared with the normal control group, the P131R group had a significant reduction in the expression of SLC26A3 protein (P=0.001)., Conclusions: SLC26A3 c.392C>G (p.P131R) can reduce the expression of SLC26A3 protein, increase the monolayer permeability of intestinal epithelial cells, and thus lead to diarrhea.

Congenital chloride diarrhea (CCD) is an autosomal recessive hereditary disease manifested by persistent, watery, profuse diarrhea with high chloride concentration (>90 mmol/L). Postnatally, neonates suffer from hypochloremia, hyponatremia, hypokalemia, metabolic alkalosis, dehydration, developmental retardation, or even death. Prenatal diagnosis is of great importance for the prognosis of CCD. We report a prenatal recurrent case of CCD. Prenatal ultrasound revealed fetal diffuse intestinal dilation with the typical honeycomb sign and polyhydramnios with high amniotic fluid index. The whole exome capture and massively-parallel DNA sequencing showed an abnormal mutation of Solute Carrier Family 26, Member 3 (SLC26A3), c.1039G>A (p.Ala347Thr), and the mutation sites were verified by sanger sequencing. When prenatal ultrasound shows polyhydramnios and diffuse intestinal dilation, CCD should be suspected. Molecular genetic testing can be helpful for the diagnosis., (© 2019 The Authors. Journal of Obstetrics and Gynaecology Research published by John Wiley & Sons Australia, Ltd on behalf of Japan Society of Obstetrics and Gynecology.)

Objective: To clarify clinical and genetic features of Japanese children with congenital chloride diarrhea (CCD)., Study Design: This was a multi-institutional, retrospective survey of 616 pediatric centers in Japan with identified patients with CCD between 2014 and 2018. Mutations involving SLC26A3 were detected by Sanger sequencing., Results: Thirteen patients met all entry criteria including mutations in SLC26A3, and 14 patients satisfied clinical diagnostic criteria. Homozygous or compound heterozygous mutations in SLC26A3, including 6 novel mutations, were identified in 13 of these 14 patients (93%). The most common (detected in 7 of 13) was c.2063-1g>t. Median age at diagnosis was 1 day. Nine of the patients meeting all criteria were diagnosed as neonates (69%). Median follow-up duration was 10 years. When studied, 8 patients had <5 stools daily (62%), and all had fewer than in infancy. Only 1 patient had nephrocalcinosis, and 3 (23%) had mild chronic kidney disease. Neurodevelopment was generally good; only 1 patient required special education. Five patients (38%) received long-term sodium, potassium, and chloride supplementation., Conclusions: Early fetal ultrasound diagnosis and prompt long-term sodium, potassium, and chloride supplementation were common management features. Genetic analysis of SLC26A3 provided definitive diagnosis of CCD. In contrast with previously reported localities, c.2063-1g>t might be a founder mutation in East Asia., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Congenital Sodium Diarrhea (CSD) due to SLC9A3 mutation is a rare cause of neonatal diarrhea explained by dysfunction of the Na+/H+ antiporter 3 in intestine. To date only 10 patients have been described. We report a male patient with typical antenatal symptoms (polyhydramnios and intestinal dilation) and neonatal diarrhea with fecal sodium and bicarbonates loss. Next generation sequencing revealed a missense homozygous mutation in exon 6 of the SLC9A3 gene (NM&#95;004174.3:c.1039G > A, NP&#95;004165.2:p.Glu347Lys). Oral electrolytes supplements (Sodium and Bicarbonates) allowed a normal growth to the child currently aged twenty months. CSD symptomatology usually begins during third trimester of pregnancy. Antenatal signs are polyhydramnios and diffuse intestinal dilation. Main differential diagnoses are intestinal obstruction and Congenital Chloride Diarrhea. Diarrhea begins from the first days of life and its severity is variable. Based on the report and on the literature we suggest that non syndromic CSD can be detected during third trimester of pregnancy. With adequate electrolytes supplementation good evolution is possible., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Neurogenin3 (NEUROG3) is required for endocrine lineage formation of the pancreas and intestine. Patients with NEUROG3 mutations are born with congenital malabsorptive diarrhea due to complete loss of enteroendocrine cells, whereas endocrine pancreas development varies in an allele-specific manner. These findings suggest a context-dependent requirement for NEUROG3 in pancreas versus intestine. We utilized human tissue differentiated from NEUROG3 -/- pluripotent stem cells for functional analyses. Most disease-associated alleles had hypomorphic or null phenotype in both tissues, whereas the S171fsX68 mutation had reduced activity in the pancreas but largely null in the intestine. Biochemical studies revealed NEUROG3 variants have distinct molecular defects with altered protein stability, DNA binding, and gene transcription. Moreover, NEUROG3 was highly unstable in the intestinal epithelium, explaining the enhanced sensitivity of intestinal defects relative to the pancreas. These studies emphasize that studies of human mutations in the endogenous tissue context may be required to assess structure-function relationships., (Copyright © 2019 Elsevier Inc. All rights reserved.)