Introduction Chronic intestinal pseudo-obstruction(CIPO),defined as chronic constipation without mechanical obstruction of the gastrointesti-nal tract[1,2],often presents with a truly chameleon-like symp-tomatology including irregular defecation,abdominal pain and distension,nausea,vomiting,and sometimes fluid/electrolyte imbalance.Although diarrhea was found in ≤17％of CIPO cases,its nature,however,has not been precisely described.Serious deviations of electrolyte and acid-base status,to the best of our knowledge,have not been reported.

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_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.

Congenital Chloride Diarrhea (CCD) is a rare autosomalrecessive disorder primarily characterized by severe watery diarrhea and fecal loss of large amounts of chloride. Maintaining adequate chloride status in adolescent CCDpatients is achieved by oral NaCl and KCl containing 3-4 mmol chloride/kg body weight/day. The best available control of chloride status is measuring chloride excretion in 24-hour urine collections. We here report a now twenty year-old caucasian CCD-patient with a compound heterozygous mutation in the SLC26A3 gene who presented with severe growth-retardation as evidenced by a Standard Deviation Score (SDS) for height of -3.57. His serum choride concentration was as low as 73 mmol/L and no chloride was detectable in his urine on many occasions over several years. Based on these laboratory findings the patient was repeatedly instructed to increase his salt intake which finally resulted in as much as six times the recommended dose of chloride, i.e.more than 20 - 25 mmol/kg/d. Only then he achieved measurable amounts of chloride in his urine and regained age-adequate growth. This paper should alert physicians to the possibility that in certain CCD patients salt intake reports in conjunction with laboratory results may falsely indicate the need for a much higher than usual chloride supplementation than hitherto reported. While non-compliance in adhering to physician´s prescriptions is believed to be the most probable cause, other potential etiologies, including medications driving chloride excretion, gut resection, infection/inflammation and novel as yet undiscovered genetic disorders in addition to SLC26A3-mutations should not be neglected.

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.

Congenital diarrheal disorders (CDD) comprise > 50 monogenic entities featuring chronic diarrhea of early-onset, including defects in nutrient and electrolyte absorption, enterocyte polarization, enteroendocrine cell differentiation, and epithelial integrity. Diarrhea is also a predominant symptom in many immunodeficiencies, congenital disorders of glycosylation, and in some defects of the vesicular sorting and transporting machinery. We set out to identify the etiology of an intractable diarrhea in 2 consanguineous families by whole-exome sequencing, and identified two novel AP1S1 mutations, c.269T>C (p.Leu90Pro) and c.346G>A (p.Glu116Lys). AP1S1 encodes the small subunit of the adaptor protein 1 complex (AP-1), which plays roles in clathrin coat-assembly and trafficking between trans-Golgi network, endosomes and the plasma membrane. An AP1S1 knock-out (KO) of a CaCo2 intestinal cell line was generated to characterize intestinal AP1S1 deficiency as well as identified mutations by stable expression in KO background. Morphology and prototype transporter protein distribution were comparable between parental and KO cells. We observed altered localization of tight-junction proteins ZO-1 and claudin 3, decreased transepithelial electrical resistance and an increased dextran permeability of the CaCo2-AP1S1-KO monolayer. In addition, lumen formation in 3D cultures of these cells was abnormal. Re-expression of wild-type AP1S1 in CaCo2-AP1S1-KO cells reverted these abnormalities, while expression of AP1S1 containing either missense mutation did not. Our data indicate that loss of AP1S1 function causes an intestinal epithelial barrier defect, and that AP1S1 mutations can cause a non-syndromic form of congenital diarrhea, whereas 2 reported truncating AP1S1 mutations caused MEDNIK syndrome, characterized by mental retardation, enteropathy, deafness, neuropathy, ichthyosis, and keratodermia.

Abstract Background Congenital chloride diarrhea (CLD) is a rare autosomal recessive disease caused by the mutation in member 3 of the solute carrier 26 (SLC26A3). The phenotypic expression is a life-long severe watery Chloride rich diarrhea. Anecdotal association with inflammatory bowel disease (IBD) has been reported suggesting that underlying molecular mechanisms could represent part of an evolving association between IBD and channelopathies. We aimed to investigate this association in a cohort of CLD pediatric patients. Methods A European-based call for cases was made in CLD patients followed up in five different countries. A case report form for each patient was then completed. Results A total of 74 patients with CLD with a range of different CLD mutations were enrolled in the study. Twelve patients of 64 (16%) demonstrated colonic inflammation and were finally diagnosed with IBD: 8 patients with Crohn’s Disease, 2 with Ulcerative Colitis, and 2 IBD-like colitis (IBD-U). The diagnosis was made at a median of 12 years old (IQR: 6–30). Patients had different ethnicities (7 European, 2 Middle East, 1 North Africa, 1 Pakistan, 1 Central Africa). Among the 12 IBD, 2 had a 5-ASA-based treatment, 3 required immunosuppressant and 6 had biologics (Infliximab, Adalimumab and Vedolizumab). Three patients underwent surgery for ileostomy formation for CD that was non-responsive to multiple line of biologics (anti-TNF and anti-integrin): one had colectomy the remnant two colon preservation. Clinical characteristics, such as premature delivery, low weight at birth, fecal Cl- at diagnosis and amount of Cl- supplementation (mmol/kg) did not differ between patients with or without IBD. All patients underwent genotyping for CLD diagnosis and we did not find any specific genetic mutation linked to the development of IBD. Conclusion Sixteen percent of patients enrolled with CLD in our cohort developed IBD. Despite different presentations (CD, UC, IBD-U) all patients had colonic without ileal/small bowel involvement, in line with preliminary murine models of CLD demonstrating a role of colonic mucous layer in the development of colonic inflammation (Xiao et al Acta Physiol Oxf Engl 2014; 211:161–175). Patients’ IBD treatment included a wide range with variable success. Patients with IBD did not differ in their clinical characteristics or genetic mutations compared with non-IBD CLD patients. The role of genetic variants outside the CLD-gene and the microbiome in this association are under investigation.

Background: Choanal (CA) and gastrointestinal atresias (GA) are an important feature of syndromic congenital sodium diarrhea (sCSD), a disorder recently associated with mutations in the gene for serine protease inhibitor type 2 (SPINT2). It is, however, not known whether isolated non-syndromic CA and GA themselves might result from SPINT2 mutations. Methods: We performed a prospective cohort study to investigate 19 CA and/or GA patients without diarrhea ("non-sCSD") for potential sCSD characteristic clinical features and SPINT2 mutations. Results: We found a heterozygous SPINT2 splice mutation (c.593-1G>A), previously demonstrated in sCSD in homozygous form, in only 1 of the 19 patients of the "non-sCSD" cohort. This patient presented with isolated anal atresia and borderline low laboratory parameters of sodium balance. In the remaining 18 non-sCSD CA/GA patients investigated, SPINT2 sequence analysis and clinical markers of sodium homeostasis were normal. None of the 188 healthy controls tested in a regional Tyrolean population harbored the c.593-1G>A mutation, which is also not listed in the ExAc and gnomAD databases. Conclusions: The finding of only one heterozygous SPINT2 mutation in 19 patients with isolated CA/GA was not statistically significant. Therefore, SPINT2 mutations are an unlikely cause of non-sCSD atresia. Trial registration ISRCTN73824458. Retrospectively registered 28 September 2014

The syndromic form of congenital sodium diarrhea (SCSD) is caused by bi-allelic mutations in SPINT2, which encodes a Kunitz-type serine protease inhibitor (HAI-2). We report three novel SCSD patients, two novel SPINT2 mutations and review published cases. The most common findings in SCSD patients were choanal atresia (20/34) and keratitis of infantile onset (26/34). Characteristic epithelial tufts on intestinal histology were reported in 13/34 patients. Of 13 different SPINT2 variants identified in SCSD, 4 are missense variants and localize to the second Kunitz domain (KD2) of HAI-2. HAI-2 has been implicated in the regulation of the activities of several serine proteases including prostasin and matriptase, which are both important for epithelial barrier formation. No patient with bi-allelic stop mutations was identified, suggesting that at least one SPINT2 allele encoding a protein with residual HAI-2 function is necessary for survival. We show that the SCSD-associated HAI-2 variants p.Phe161Val, p.Tyr163Cys and p.Gly168Ser all display decreased ability to inhibit prostasin-catalyzed cleavage. However, the SCSD-associated HAI-2 variants inhibited matriptase as efficiently as the wild-type HAI-2. Homology modeling indicated limited solvent exposure of the mutated amino acids, suggesting that they induce misfolding of KD2. This suggests that prostasin needs to engage with an exosite motif located on KD2 in addition to the binding loop (Cys47/Arg48) located on the first Kunitz domain in order to inhibit prostasin. In conclusion our data suggests that SCSD is caused by lack of inhibition of prostasin or a similar protease in the secretory pathway or on the plasma membrane.

Diseases causing hematochezia range from benign to potentially life-threatening. Systematic pediatric data on the causes of hematochezia are scarce. We studied the underlying causes and long-term outcome of hematochezia in children. We further investigated the relevance of antibiotic-associated hemorrhagic colitis in children, especially if caused by Klebsiella oxytoca.Infants, children, and adolescents with hematochezia were recruited prospectively. Patients were grouped according to age (<1 year, 1-5 years, 6-13 years, >14 years). In addition to routine diagnostics, K oxytoca stool culture and toxin analysis was performed. We collected data on history, laboratory findings, microbiological diagnostic, imaging, final diagnosis, and long-term outcome.We included 221 patients (female 46%; age 0-19 years). In 98 (44%), hematochezia was caused by infectious diseases. Endoscopy was performed in 30 patients (13.6%). No patient died due to the underlying cause of hematochezia. The most common diagnoses according to age were food protein-induced proctocolitis in infants, bacterial colitis in young children, and inflammatory bowel disease in children and adolescents. Seventeen (7.7%) had a positive stool culture for K oxytoca. Antibiotic-associated colitis was diagnosed in 12 (5%) patients: 2 caused by K oxytoca and 2 by Clostridium difficile; in the remaining 8 patients, no known pathobiont was identified.Infections were the most common cause of hematochezia in this study. In most patients, invasive diagnostic procedures were not necessary. Antibiotic-associated hemorrhagic colitis caused by K oxytoca was an uncommon diagnosis in our cohort. Antibiotic-associated colitis with hematochezia might be caused by pathobionts other than C difficile or K oxytoca.

OBJECTIVE:Congenital sodium diarrhoea (CSD) refers to a form of secretory diarrhoea with intrauterine onset and high faecal losses of sodium without congenital malformations. The molecular basis for CSD remains unknown. We clinically characterised a cohort of infants with CSD and set out to identify disease-causing mutations by genome-wide genetic testing.DESIGN:We performed whole-exome sequencing and chromosomal microarray analyses in 4 unrelated patients, followed by confirmatory Sanger sequencing of the likely disease-causing mutations in patients and in their family members, followed by functional studies.RESULTS:We identified novel de novo missense mutations in GUCY2C, the gene encoding receptor guanylate cyclase C (GC-C) in 4 patients with CSD. One patient developed severe, early-onset IBD and chronic arthritis at 4 years of age. GC-C is an intestinal brush border membrane-bound guanylate cyclase, which functions as receptor for guanylin, uroguanylin and Escherichia coli heat-stable enterotoxin. Mutations in GUCY2C were present in different intracellular domains of GC-C, and were activating mutations that enhanced intracellular cyclic guanosine monophosphate accumulation in a ligand-independent and ligand-stimulated manner, following heterologous expression in HEK293T cells.CONCLUSIONS:Dominant gain-of-function GUCY2C mutations lead to elevated intracellular cyclic guanosine monophosphate levels and could explain the chronic diarrhoea as a result of decreased intestinal sodium and water absorption and increased chloride secretion. Thus, mutations in GUCY2C indicate a role for this receptor in the pathogenesis of sporadic CSD.

Lactose malabsorption (LM) is caused by insufficient enzymatic degradation of the disaccharide by intestinal lactase. Although hydrogen (H-2) breath tests (HBTs) are routinely applied to diagnose LM, false-negative results are not uncommon.Thirty-two pediatric patients (19 females, 13 males) were included in this prospective study. After oral lactose administration (1 g kg(-1) bodyweight to a maximum of 25 g), breath H-2 was measured by electrochemical detection. HBT was considered positive if H-2 concentration exceeded an increase of >= 20 ppm from baseline. In addition to H-2, exhaled methane (CH4), blood glucose concentrations and clinical symptoms (flatulence, abdominal pain, diarrhea) were monitored.A positive HBT indicating LM was found in 12/32 (37.5%) patients. Only five (41.7%, 5/12) of these had clinical symptoms during HBT indicating lactose intolerance (LI). Decreased blood glucose concentration increments (<= 20 mg dL(-1) (<= 1.1 mmol L-1)) were found in 3/5 of these patients. CH4 concentrations >= 10 ppm at any time during the test were observed in 5/32 (15.6%) patients and in 9/32 (28.1%) between 1 ppm and 9 ppm above baseline after lactose ingestion. In patients with positive HBT 10/12 (83.3%) showed elevated CH4 (>1 ppm) above baseline in breath gas, whereas in patients with negative HBT this figure was only 4/17 (23.5%).In addition to determining H-2 in exhaled air, documentation of clinical symptoms, measurement of blood glucose and breath CH4 concentrations may be helpful in deciding whether in a given case an HBT correctly identifies patients with clinically relevant LM.

Congenital diarrheal disorders (CDDs) represent a group of challenging clinical conditions for pediatricians because of the severity of the presentation and the broad range of possible differential diagnoses. CDDs arise from alterations in the transport of nutrients and electrolytes across the intestinal mucosa, from enterocyte and enteroendocrine cell differentiation and/or polarization defects, and from the modulation of the intestinal immune response. Advances were made recently in deciphering the etiology and pathophysiology of one of these disorders, congenital sodium diarrhea (CSD). CSD refers to an intractable diarrhea of intrauterine onset with high fecal sodium loss. CSD is clinically and genetically heterogeneous. A syndromic form of CSD features choanal and intestinal atresias as well as recurrent corneal erosions. Small bowel histology frequently detects an epithelial "tufting'' dysplasia. It is autosomal recessively inherited, and caused by SPINT2 mutations. The nonsyndromic form of CSD can be caused by dominant activating mutations in GUCY2C, encoding intestinal receptor guanylate cyclase C (GC-C), and by autosomal recessive SLC9A3 loss-of-function mutations. SLC9A3 encodes Na+/H+ antiporter 3, the major intestinal brush border Na+/H+ exchanger, and a downstream target of GC-C. A number of patients with GUCY2C and SLC9A3 mutations developed inflammatory bowel disease. Both the number of recognized CDD forms as well as the number of underlying disease genes are gradually increasing. Knowledge of these CDD genes enables noninvasive, next-generation gene panel-based testing to facilitate an early diagnosis in CDD. Primary Na+/H+ antiporter 3 and GC-C malfunction is implicated as a predisposition for inflammatory bowel disease in subset of patients.

BACKGROUND:Rotavirus (RV)-associated infections account for high numbers of hospitalizations in neonates and young infants. Universal mass vaccination (UMV) has been shown to prevent the burden of disease in vaccinated children.METHODS:The present study investigated the long-term effects of UMV on RV-associated hospitalizations in children with particular focus on neonates and young infants (≤42 days old) not eligible for vaccination. Ten years of Austrian surveillance data were compared, including 10 960 laboratory-confirmed RV cases before (prevaccination period [PreVP]) and after (postvaccination period [PostVP]) introduction of UMV.RESULTS:A postvaccination decrease in hospitalized community-acquired RV infections by 89.3% was seen in all age groups, including unvaccinated neonates and young infants. Of the latter, 27.6% had a nosocomial RV infection in PreVP, and 19.3% in PostVP. Overall, the proportion of nosocomial RV infections increased from 5.5% in PreVP to 13.0% in PostVP. Breakthrough infections, usually after incomplete RV vaccination, could be identified in 6.2% of patients.CONCLUSIONS:Unvaccinated neonates and infants ≤42 days old may indirectly benefit from UMV by reduction of RV infections. Breakthrough infections underline the importance of early and complete protection by the vaccine. In older patients, heightened awareness of nosocomial RV infections is warranted. Identification of RV reservoirs is also needed.

Background: In CF infants, normonatremic Na+ depletion (NNaD), identified by fractional Na+ excretion (FENa) values <0.5%, was recently linked to impaired growth. Our paper investigates the relationship between FENa and growth in CF children >2 years.Methods: FENa values were calculated in 35 CF and 24 control children, and tested for correlations with z-scores for weight, height and BMI.Results: All CF children and controls had normal plasma Na+ concentrations. A total of 25 of 35 (71.4%) CF patients had decreased FENa values <0.5% (group I). FENa results of 10 CF patients (group II) and 23/24 controls (group III) were normal. In Na+-depleted CF children, compared to normal controls, mean z-scores for weight (-0.18 +/- 0.87 vs +1.03 +/- 0.57, p < 0.001), height (-0.06 +/- 0.89 vs +0.53 +/- 0.72, p = 0.009) and BMI (-0.22 +/- 0.87 vs +1.00 +/- 1.06, p < 0.001) were significantly reduced. Also, we found positive correlations between FENa values and z-scores for weight (r = 0.521), height (r = 0.292) and BMI (r = 0.468), respectively.Conclusion: NNaD may contribute to poor growth in CF. (C) 2016 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

Myo5b null mice display microvillus inclusions. Ezrin and p120 immunostaining were assessed in Myo5b null and wild type littermate mice. In a wildtype littermate, ezrin (left panel and red-right panel) was only expressed on the apical surface of the enterocytes. In all Myo5b null mice examined to date, ezrin was found in inclusions within the enterocytes. p120 localization (green-right panel) was unchanged in null mice. Heterozygote mice were identical to wild type mice and did not show microvillus inclusions. Scale bars = 50 μm.

In acute gastroenteritis (AG) fecal losses may cause depletion of sodium (NaD) which may not be recognized because of normal plasma Na (pNa) concentrations. We studied the incidence of this state of normonatremic sodium depletion (NNaD) and the suitability of the urinary Na/urinary creatinine ratio (uNa/uCr) for diagnosing NNaD.Patients: 16 AG- and 16 healthy control children aged 0.8-15.0 years.Methods: Prospective cross sectional pilot study. Measurements of Na, K and creatinine in plasma (p) and urine (u). Calculation of uNa/uCr Ratio, fractional excretion of Na (FENa) and uNa/uK ratio as the hitherto best known parameters of prerenal Na depletion, respectively.Results: pNa concentrations were normal in 15/16 AG patients (93.8%) with only one subnormal value of 133mmol/L, and a mean value of 137.92.3mmol/L not different from the normal control group (139.42.2mmol/L). Also, mean uNa concentrations and uNa/uK ratios did not differ between both groups. However, uNa/uCr ratios were below normal in 13/16 AG children (81.3%) but normal in all healthy controls with a significantly lower mean value in the AG group (12.68.8 vs. 31.28.3mmol/mmol; p<0.0001). Similarly, 14/16 AG patients (87.5%) had a decreased FENa<0.5% with a mean FENa value significantly lower than in controls (0.360.28% vs. 0.950.26%, p<0.0001). The good agreement between FENa and uNa/uCr results was also reflected by a high correlation coefficient of r=0.9333.Conclusions: The majority of AG patients was found to have NNaD as determined by uNa/uCr and FENa. Calculation of uNa/uCr may be useful for diagnosing NNaD in AG.

Myo5b null mice display microvillus inclusions. Ezrin and p120 immunostaining were assessed in Myo5b null and wild type littermate mice. In a wildtype littermate, ezrin (left panel and red-right panel) was only expressed on the apical surface of the enterocytes. In all Myo5b null mice examined to date, ezrin was found in inclusions within the enterocytes. p120 localization (green-right panel) was unchanged in null mice. Heterozygote mice were identical to wild type mice and did not show microvillus inclusions. Scale bars = 50 μm.

Congenital sodium diarrhea (CSD) refers to an intractable diarrhea of intrauterine onset with high fecal sodium loss. CSD is clinically and genetically heterogeneous. Syndromic CSD is caused by SPINT2 mutations. While we recently described four cases of the non-syndromic form of CSD that were caused by dominant activating mutations in intestinal receptor guanylate cyclase C (GC-C), the genetic cause for the majority of CSD is still unknown. Therefore, we aimed to determine the genetic cause for non-GC-C non-syndromic CSD in 18 patients from 16 unrelated families applying whole-exome sequencing and/or chromosomal microarray analyses and/or direct Sanger sequencing. SLC9A3 missense, splicing and truncation mutations, including an instance of uniparental disomy, and whole-gene deletion were identified in nine patients from eight families with CSD. Two of these nine patients developed inflammatory bowel disease (IBD) at 4 and 16 years of age. SLC9A3 encodes Na(+)/H(+) antiporter 3 (NHE3), which is the major intestinal brush-border Na(+)/H(+) exchanger. All mutations were in the NHE3 N-terminal transport domain, and all missense mutations were in the putative membrane-spanning domains. Identified SLC9A3 missense mutations were functionally characterized in plasma membrane NHE null fibroblasts. SLC9A3 missense mutations compromised NHE3 activity by reducing basal surface expression and/or loss of basal transport function of NHE3 molecules, whereas acute regulation was normal. This study identifies recessive mutations in NHE3, a downstream target of GC-C, as a cause of CSD and implies primary basal NHE3 malfunction as a predisposition for IBD in a subset of patients.