Congenital diarrheal disorders: an updated diagnostic approach. Int J Mol Sci. 2012;13:4168-4185. [PMID: 22605972 PMCID: PMC3344208 DOI: 10.3390/ijms13044168]

Diet and Management of Diarrhea

Diet plays an important role in human health and disease. Of all human diseases, diarrheal illnesses bring diet into sharp focus as it has a direct causal and therapeutic relationship. With the advent and widespread use of next generation sequencing, significant advances have been made in unraveling the etiologies of congenital diarrheas and enteropathies, some of which are eminently treatable with dietary modification. Early institution of appropriate dietary therapy is lifesaving in congenital osmotic diarrheas. Chronic diarrhea in older children and adolescents often have an underlying dietary basis, depending on the etiology. Identification and exclusion of the offending food in the diet results in dramatic improvement in symptoms. It is equally important to be prudent and cautious in the use of exclusion diets in management of chronic diarrhea as it is associated with micronutrient deficiencies, needless escalation of cost and enable maladaptive food intake behaviors. In this review, authors discuss etiology specific dietary management of diarrhea in children with emphasis on congenital diarrheas and enteropathies.

Intractable diarrhea in infancy and molecular analysis: We are beyond the tip of the iceberg

BACKGROUND

Intractable diarrhea (ID) could be defined as a syndrome of severe chronic diarrhea associated with malnutrition not easily resolved by conventional management.

AIMS

To provide an overview on etiology and management of ID patients in Italy in the last 12 years.

METHODS

The members of Italian Society for Pediatric Gastroenterology, Hepatology and Nutrition (SIGENP) enrolled all ID patients seen between January 1, 2011 and December 31, 2022.

RESULTS

69 children were enrolled (49 M, 20 F; median age at ID onset 9.5 days) from 7 tertiary care pediatric centers. Overall 62 patients had genetic diseases; 3 had infantile Inflammatory Bowel Disease and 1 autoimmune enteropathy in absence of genetic mutations; 2 undefined ID. Defects of intestinal immune-related homeostasis caused ID in 29 patients (42 %).

CONCLUSION

ID is a rare but challenging problem, although the potential for diagnosis has improved over time. In particular, molecular analysis allowed to identity genetic defects in 90 % of patients and to detect new genetic mutations responsible for ID. Due to both the challenging diagnosis and the treatment for many of these diseases, the close relationship between immune system and digestive tract should require a close collaboration between pediatric immunologists and gastroenterologists, to optimize epidemiologic surveillance and management of ID.

Homozygous Missense Epithelial Cell Adhesion Molecule Variant in a Patient with Congenital Tufting Enteropathy and Literature Review

Congenital diarrheal disorders (CDDs) with genetic etiology are uncommon hereditary intestinal diseases characterized by chronic, life-threatening, intractable watery diarrhea that starts in infancy. CDDs can be mechanistically divided into osmotic and secretory diarrhea. Congenital tufting enteropathy (CTE), also known as intestinal epithelial dysplasia, is a type of secretory CDD. CTE is a rare autosomal recessive enteropathy that presents with intractable neonatal-onset diarrhea, intestinal failure, severe malnutrition, and parenteral nutrition dependence. Villous atrophy of the intestinal epithelium, crypt hyperplasia, and irregularity of surface enterocytes are the specific pathological findings of CTE. The small intestine and occasionally the colonic mucosa include focal epithelial tufts. In 2008, Sivagnanam et al. discovered that mutations in the epithelial cell adhesion molecule (EpCAM, MIM# 185535) were the genetic cause of CTE (MIM# 613217). More than a hundred mutations have been reported to date. Furthermore, mutations in the serine peptidase inhibitor Kunitz type 2 (SPINT2, MIM# 605124) have been linked to syndromic CTE. In this study, we report the case of a 17-month-old male infant with congenital diarrhea. Despite extensive etiological workup, no etiology could be established before admission to our center. The patient died 15 hours after being admitted to our center in a metabolically decompensated state, probably due to a delay in admission and diagnosis. Molecular autopsy with exome sequencing revealed a previously reported homozygous missense variant, c.757G>A, in EpCAM, which was confirmed by histopathological examination.

Early onset congenital diarrheas; single center experience

BACKGROUND

Congenital diarrheal disorders (CDDs) are a rare group of enteropathies that typically present in the early few months of life and pose a diagnostic challenge. We aimed to analyze the clinical findings and outcome of infants with CDDs and share experience about genetic testing.

METHODS

Demographic, clinical and genetic findings, and outcome of the patients (n = 24) with CDDs were recorded from hospital files.

RESULTS

The onset of diarrhea was within the neonatal period in 45.8% of the patients. The most frequent causes of CDDs were defects in digestion, absorption and transport of nutrients and electrolytes (DATN) (n = 11, 45.8%) and defects in intestinal immune-related homeostasis (IIH) (n = 6, 25%). Fat malabsorption (n = 6) was the leading cause of defects in DATN. Extraintestinal manifestations including neurological involvement (25%) and renal involvement (20.8%) were common among the patients. Genetic analyses were performed for 16 patients (targeted gene analysis in 9, congenital diarrhea panel in 3, immune deficiency panel in 1 and whole-exome sequencing in 3 patients). Genetic diagnosis was achieved in 14 of 16 patients (87.5%) with therapeutic consequences in 8 of 16 patients (50%). During the follow-up, 6 patients (25%) died.

CONCLUSION

The percentage of undefined etiology decreased, and treatment of the patients improved with the increased number of genetic testing in patients with CDDs.

Microvillous inclusion disease as a cause of severe congenital diarrhea in a newborn

Microvillous inclusion disease (MVID), also known as congenital microvillus atrophy remains an important differential diagnosis of intractable secretory diarrhea in neonatal period. The condition is inherited as an autosomal recessive disorder with no sex predilection and more commonly reported in those tribes with consanguineous marriages. The pathognomonic electron microscopic findings includes villous atrophy with the formation of intracellular microvillous inclusions. Definite treatment includes either isolated small bowel or combined small bowel and liver transplantation. Herein, we are describing a case of intractable diarrhea in a preterm neonate with MVID phenotype presented on second day of life with intractable diarrhea. The diagnosis was established by classical electron microscopic findings in the intestinal biopsy sample.

Etiology and Management of Pediatric Intestinal Failure: Focus on the Non-Digestive Causes

Background: Intestinal failure (IF) is defined as reduction in functioning gut mass below the minimal amount necessary for adequate digestion and absorption. In most cases, IF results from intrinsic diseases of the gastrointestinal tract (digestive IF) (DIF); few cases arise from digestive vascular components, gut annexed (liver and pancreas) and extra-digestive organs or from systemic diseases (non-digestive IF) (NDIF). The present review revised etiology and treatments of DIF and NDIF, with special focus on the pathophysiological mechanisms, whereby NDIF develops. Methods: We performed a comprehensive search of published literature from January 2010 to the present by selecting the following search strings: “intestinal failure” OR “home parenteral nutrition” OR “short bowel syndrome” OR “chronic pseudo-obstruction” OR “chronic intestinal pseudo-obstruction” OR “autoimmune enteropathy” OR “long-term parenteral nutrition”. Results: We collected overall 1656 patients with well-documented etiology of IF: 1419 with DIF (86%) and 237 with NDIF (14%), 55% males and 45% females. Among DIF cases, 66% had SBS and among NDIF cases 90% had malabsorption/maldigestion. Conclusions: The improved availability of diagnostic and therapeutic tools has increased prevalence and life expectancy of rare and severe diseases responsible for IF. The present review greatly expands the spectrum of knowledge on the pathophysiological mechanisms through which the diseases not strictly affecting the intestine can cause IF. In view of the rarity of the majority of pediatric IF diseases, the development of IF Registries is strongly required; in fact, through information flow within the network, the Registries could improve IF knowledge and management.

NGS Gene Panel Analysis Revealed Novel Mutations in Patients with Rare Congenital Diarrheal Disorders

Congenital diarrheal disorders (CDDs) are early-onset enteropathies generally inherited as autosomal recessive traits. Most patients with CDDs require rapid diagnosis as they need immediate and specific therapy to avoid a poor prognosis, but their clinical picture is often overlapping with a myriad of nongenetic diarrheal diseases. We developed a next-generation sequencing (NGS) panel for the analysis of 92 CDD-related genes, by which we analyzed patients suspect for CDD, among which were (i) three patients with sucrose-isomaltase deficiency; (ii) four patients with microvillous inclusion disease; (iii) five patients with congenital tufting enteropathy; (iv) eight patients with glucose-galactose malabsorption; (v) five patients with congenital chloride diarrhea. In all cases, we identified the mutations in the disease-gene, among which were several novel mutations for which we defined pathogenicity using a combination of bioinformatic tools. Although CDDs are rare, all together, they have an incidence of about 1%. Considering that the clinical picture of these disorders is often confusing, a CDD-related multigene NGS panel contributes to unequivocal and rapid diagnosis, which also reduces the need for invasive procedures.

Congenital Tufting Enteropathy: Biology, Pathogenesis and Mechanisms

Congenital tufting enteropathy (CTE) is an autosomal recessive disease of infancy that causes severe intestinal failure with electrolyte imbalances and impaired growth. CTE is typically diagnosed by its characteristic histological features, including villous atrophy, crypt hyperplasia and focal epithelial tufts consisting of densely packed enterocytes. Mutations in the EPCAM and SPINT2 genes have been identified as the etiology for this disease. The significant morbidity and mortality and lack of direct treatments for CTE patients demand a better understanding of disease pathophysiology. Here, the latest knowledge of CTE biology is systematically reviewed, including clinical aspects, disease genetics, and research model systems. Particular focus is paid to the pathogenesis of CTE and predicted mechanisms of the disease as these would provide insight for future therapeutic options. The contribution of intestinal homeostasis, including the role of intestinal cell differentiation, defective enterocytes, disrupted barrier and cell-cell junction, and cell-matrix adhesion, is vividly described here (see Graphical Abstract). Moreover, based on the known dynamics of EpCAM signaling, potential mechanistic pathways are highlighted that may contribute to the pathogenesis of CTE due to either loss of EpCAM function or EpCAM mutation. Although not fully elucidated, these pathways provide an improved understanding of this devastating disease.

Moving on: How to switch young people with chronic intestinal failure from pediatric to adult care. a position statement by italian society of gastroenterology and hepatology and nutrition (SIGENP) and italian society of artificial nutrition and metabolism (SINPE)

In 2019 the Italian Society of Pediatric Gastroenterology, Hepatology and Nutrition (SIGENP) and the Italian Society of Artificial Nutrition and Metabolism (SINPE) created a joint panel of experts with the aim of preparing an official statement on transition in Chronic Intestinal Failure (CIF). The transition from pediatric to adult care has a key role in managing all chronic diseases and in optimizing the compliance to care. Thus SIGENP and SINPE, in light of the growing number of patients with IF who need long-term Parenteral Nutrition (PN) and multidisciplinary rehabilitation programs throughout adulthood, shared a common protocol to provide an accurate and timely process of transition from pediatric to adult centers for CIF. The main objectives of the transition process for CIF can be summarized as the so-called "acronym of the 5 M": 1)Motivate independent choices which are characteristics of the adult world; 2)Move towards adult goals (e.g. self-management of his pathology and sexual issues); 3)Maintain the habitual mode of care; 4) Minimize the difficulties involved in the transition process and 5)Modulate the length of the transition so as to fully share with the adult's team the children's peculiarities.

Tufting Enteropathy: A Review of Clinical and Histological Presentation, Etiology, Management, and Outcome

Congenital tufting enteropathy (CTE), also named intestinal epithelial dysplasia, is a rare, autosomal recessive enteropathy with persistent and life-threatening intractable diarrhea early in life. Intractable diarrhea is present independent of breast or formula feeding. Most CTE patients require total parenteral nutrition (TPN), and in severe cases, small bowel transplantation is needed. In the last decade, we have seen remarkable progress in certain aspects, such as the pathogenesis and diagnostic methods of the disease. Rapidly developing molecular analysis techniques have improved the diagnostic methods for CTE and reduced invasive and expensive procedures. Mutations in the gene encoding human epithelial cell adhesion molecule (EpCAM) were identified in the typical form of CTE, which usually exhibits isolated refractory diarrhea. Moreover, the syndromic form of CTE features anal and choanal atresias as well as ophthalmologic signs, which are associated with mutations in the gene encoding Serine Peptidase Inhibitor Kunitz Type 2 (SPINT2). This article reviews CTE disease based on its clinical and histological presentation, etiology and pathogenesis, and management and outcome.

Microvillus Inclusion Disease: A Rare Mutation of STX3 in Exon 9 Causing Fatal Congenital Diarrheal Disease

Inherited diarrheal disorders cause serious morbidity resulting in dependence on intensive care and parenteral nutrition. Microvillus inclusion disease (MVID) has been classically described and results from mutations in the gene coding myosin Vb, which is responsible for enterocyte polarization. Newer reports of mutations resulting in truncated syntaxin 3 (STX3) and Munc18-2 (STXBP2) proteins have been elucidated as causative. To date, five cases of STX3 abnormalities resulting in MVID have been described. We report an infant who presented with congenital diarrhea and was determined to have a rare mutation of STX3. This new finding would be beneficial in future functional genotype–phenotype correlation studies.

Congenital chloride diarrhoea

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.

Recent advances in understanding and managing malabsorption: focus on microvillus inclusion disease

Microvillus inclusion disease (MVID) is a rare congenital severe malabsorptive and secretory diarrheal disease characterized by blunted or absent microvilli with accumulation of secretory granules and inclusion bodies in enterocytes. The typical clinical presentation of the disease is severe chronic diarrhea that rapidly leads to dehydration and metabolic acidosis. Despite significant advances in our understanding of the causative factors, to date, no curative therapy for MVID and associated diarrhea exists. Prognosis mainly relies on life-long total parenteral nutrition (TPN) and eventual small bowel and/or liver transplantation. Both TPN and intestinal transplantation are challenging and present with many side effects. A breakthrough in the understanding of MVID emanated from seminal findings revealing mutations in MYO5B as a cause for MVID. During the last decade, many studies have thus utilized cell lines and animal models with knockdown of MYO5B to closely recapitulate the human disease and investigate potential therapeutic options in disease management. We will review the most recent advances made in the research pertaining to MVID. We will also highlight the tools and models developed that can be utilized for basic and applied research to increase our understanding of MVID and develop novel and effective targeted therapies.

Congenital diarrhea in a newborn infant: A case report

BACKGROUND

Microvillus inclusion disease (MVID) is a rare autosomal recessive cause of severe congenital diarrhea with significant morbidity and mortality. Definitive treatment involves bowel transplant. The diagnosis of this condition can be challenging and a few genetic panels are available for the identification of the most common mutations. We present the case of an infant with MVID due to a mutation not reported in the literature before.

CASE SUMMARY

We report the case of an infant transferred to our institution with severe diarrhea of unknown etiology, failure to thrive, and significant metabolic derangements. An extensive work-up including stool studies for common gastrointestinal pathogens, abdominal ultrasound, esophagogastroduodenoscopy with duodenal biopsy and flexible sigmoidoscopy failed to reveal a diagnosis. Multiple dietary and formula regimens were introduced but all resulted in voluminous diarrhea. She remained on total parenteral nutrition (TPN) for the duration of her hospital stay. Genetic testing was done and she was subsequently found to have a novel mutation in the MYO5B gene [homozygous mutation for MYO5B c.1462del, p. (Ile488Leufs*93)] giving us the diagnosis of MVID. She remains on TPN while awaiting bowel transplant at the time of the compilation of this case report.

CONCLUSION

We report a novel mutation involved in MVID and highlight the importance of considering this disease when faced with a newborn presenting with life threatening diarrhea. At the time of this publication, 232 allelic variations of this gene (MIM#606540) exist in National Center for Biotechnology Information's database. Our patient's mutation has not been reported in literature as a cause of MVID.

Congenital glucose-galactose malabsorption: A case report with a novel SLC5A1 mutation

A three-day-old newborn girl presented with decreased feeding and dehydration. She was sick and in shock. She had renal impairment and hypernatremia. With the resumption of breast feeding, she developed watery stools and hypernatremia. Glucose-Galactose Malabsorption was suspected and confirmed by the presence of a likely pathogenic homozygous variant in SLC5A1.

Two cases of microvillous inclusion disease caused by novel mutations in MYO5B gene

Microvillous inclusion disease (MVID) typically appears with severe chronic diarrhea in the few days after birth and rapidly causes dehydration and metabolic acidosis. In this context, presenting two novel cases, we underline the crucial importance of mutation analysis for the diagnosis of this disease that may be easily misdiagnosed.

Reversible deficits in apical transporter trafficking associated with deficiency in diacylglycerol acyltransferase

Deficiency in diacylglycerol acyltransferase (DGAT1) is a rare cause of neonatal diarrhea, without a known mechanism or in vitro model. A patient presenting at our institution at 7 weeks of life with failure to thrive and diarrhea was found by whole-exome sequencing to have a homozygous DGAT1 truncation mutation. Duodenal biopsies showed loss of DGAT1 and deficits in apical membrane transporters and junctional proteins in enterocytes. When placed on a very low-fat diet, the patient's diarrhea resolved with normalization of brush border transporter localization in endoscopic biopsies. DGAT1 knockdown in Caco2-BBe cells modeled the deficits in apical trafficking, with loss of apical DPPIV and junctional occludin. Elevation in cellular lipid levels, including diacylglycerol (DAG) and phospholipid metabolites of DAG, was documented by lipid analysis in DGAT1 knockdown cells. Culture of the DGAT1 knockdown cells in lipid-depleted media led to re-establishment of occludin and return of apical DPPIV. DGAT1 loss appears to elicit global changes in enterocyte polarized trafficking that could account for deficits in absorption seen in the patient. The in vitro modeling of this disease should allow for investigation of possible therapeutic targets.

Prenatal Bowel Findings in Male Siblings With a Confirmed FOXP3 Mutation

There are multiple etiologies for fetal dilated bowel loops on ultrasonography (US), and we present a unique case of male siblings with a forkhead box P3 (FOXP3) mutation. Both children presented with fetal bowel anomalies on prenatal US. Family histories of cystic fibrosis and immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome were reported. Amniocentesis in both pregnancies identified a normal male karyotype and the familial mutation associated with IPEX syndrome. IPEX syndrome is one of a group of conditions known as congenital diarrhea disorders. Other congenital diarrhea disorder cases have presented with similar prenatal US findings. As a result of these associations, we suggest considering IPEX syndrome as a potential cause of fetal bowel anomalies, particularly with a known family history. However, continued research into the phenotypic and genotypic correlations for IPEX syndrome is likely needed to better understand this possible prenatal presentation.

Gastroenteritis and Intractable Diarrhea in Newborns

Gastroenteritis (GE) still represents a major cause of morbidity and mortality in children worldwide. Although the implementation of effective measures resulted in a significant decrease of global mortality, much remains to be done. The burden of GE in the neonatal age is generally reduced in relation to some protective factors (breastfeeding, minimal exposure to water and contaminated food, passive maternal immunity). In newborns, the contribution of the various causative agents could differ from that of the other pediatric age groups, nevertheless Rotavirus and pathogenic strains of E. coli remain the main etiologies. The acquisition of the pathogen generally occurs through the contaminated birth canal or by the use of contaminated tools, objects, or hands of the caregivers. The clinical presentation may vary widely from an acute, self-limiting disease to life-threatening complicated infections. The assessment of the dehydration and its rapid correction represent the cornerstones of the management of any GE. Antibiotic therapy should be reserved to cases with systemic symptoms, severe dehydration, or in the presence of bloody diarrhea. While the occurrence of diarrhea in the neonatal age is mainly caused by acute gastrointestinal infections, differential diagnosis with several other diseases including forms of severe congenital disorders should be considered.

Inflammatory Bowel Disease in Primary Immunodeficiencies

PURPOSE OF REVIEW

Inflammatory bowel disease is most often a polygenic disorder with contributions from the intestinal microbiome, defects in barrier function, and dysregulated host responses to microbial stimulation. There is, however, increasing recognition of single gene defects that underlie a subset of patients with inflammatory bowel disease, particularly those with early-onset disease, and this review focuses on the primary immunodeficiencies associated with early-onset inflammatory bowel disease.

RECENT FINDINGS

The advent of next-generation sequencing has led to an improved recognition of single gene defects underlying some cases of inflammatory bowel disease. Among single gene defects, immune response genes are the most frequent category identified. This is also true of common genetic variants associated with inflammatory bowel disease, supporting a pivotal role for host responses in the pathogenesis. This review focuses on practical aspects related to diagnosis and management of children with inflammatory bowel disease who have underlying primary immunodeficiencies.

Newcomers in paediatric GI pathology: childhood enteropathies including very early onset monogenic IBD

Childhood enteropathies are a group of diseases causing severe chronic (>2-3 weeks) diarrhoea often starting in the first week of life with the potential for fatal complications for the affected infant. Early identification and accurate classification of childhood enteropathies are, therefore, crucial for making treatment decisions to prevent life-threatening complications. Childhood enteropathies are classified into four groups based on the underlying pathology: (i) conditions related to defective digestion, absorption and transport of nutrients and electrolytes; (ii) disorders related to enterocyte differentiation and polarization; (iii) defects of enteroendocrine cell differentiation; and (iv) disorders associated with defective modulation of intestinal immune response. While the intestinal mucosa is usually normal in enteropathies related to congenital transport or enzyme deficiencies, the intestinal biopsy in other disorders may reveal a wide range of abnormalities varying from normal villous architecture to villous atrophy and/or inflammation, or features specific to the underlying disorder including epithelial abnormalities, lipid vacuolization in the enterocytes, absence of plasma cells, lymphangiectasia, microorganisms, and mucosal eosinophilic or histiocytic infiltration. This review intends to provide an update on small intestinal biopsy findings in childhood enteropathies, the "newcomers", including very early onset monogenic inflammatory bowel disease (IBD), in particular, for the practicing pathologist.

Syndromic congenital diarrhoea: new SPINT2 mutation identified in the UAE

We are reporting a new mutation in the SPINT2 gene (c.443G>A (p. Arg148His)) that explains the association of choanal atresia with congenital sodium diarrhoea (CSD) in an Emirati family in the Middle East. To our knowledge, this mutation is neither listed in a mutation database nor described in the literature. Similar to other patients with CSD associated with SPINT2, this child remains dependent on parenteral nutrition for fluids and nutritional support resulting in failure to thrive. The determination of the molecular basis of syndromic CSD will facilitate prenatal and postnatal diagnosis of patients and will contribute to counselling of affected families, especially in areas like the UAE where consanguineous marriages are not uncommon.

Twelve Novel Mutations in the SLC26A3 Gene in 17 Sporadic Cases of Congenital Chloride Diarrhea

OBJECTIVES

We aimed to improve the knowledge of pathogenic mutations in sporadic cases of congenital chloride diarrhea (CCD) and emphasize the importance of functional studies to define the effect of novel mutations.

METHODS

All member 3 of solute carrier family 26 (SLC26A3) coding regions were sequenced in 17 sporadic patients with CCD. Moreover, the minigene system was used to analyze the effect of 2 novel splicing mutations.

RESULTS

We defined the SLC26A3 genotype of all 17 patients with CCD and identified 12 novel mutations. Using the minigene system, we confirmed the in silico prediction of a complete disruption of splicing pattern caused by 2 of these novel mutations: the c.971+3_971+4delAA and c.735+4_c.735+7delAGTA. Moreover, several prediction tools and a structure-function prediction defined the pathogenic role of 6 novel missense mutations.

CONCLUSIONS

We confirm the molecular heterogeneity of sporadic CCD adding 12 novel mutations to the list of known pathogenic mutations. Moreover, we underline the importance, for laboratories that offer molecular diagnosis and genetic counseling, to perform fast functional analysis of novel mutations.

Congenital Chloride Diarrhea (CCD): A Case Report of CCD Suspected by Prenatal Ultrasonography and Magnetic Resonance Imaging (MRI)

Patient: Male, new born

Final Diagnosis: Congenital chloride diarrhea

Symptoms: Diarrhea

Medication: —

Clinical Procedure: —

Specialty: Obstetrics and Gyneolcogy

Diagnostic and Research Aspects of Small Intestinal Disaccharidases in Coeliac Disease

Disaccharidases (DS) are brush border enzymes embedded in the microvillous membrane of small intestinal enterocytes. In untreated coeliac disease (CD), a general decrease of DS activities is seen. This manuscript reviews different aspects of DS activities in CD: their utility in the diagnosis and their application to in vitro toxicity testing. The latter has never been established in CD research. However, with the recent advances in small intestinal organoid techniques, DS might be employed as a biomarker for in vitro studies. This includes establishment of self-renewing epithelial cells raised from tissue, which express differentiation markers, including the brush border enzymes. Determining duodenal DS activities may provide additional information during the diagnostic workup of CD: (i) quantify the severity of the observed histological lesions, (ii) provide predictive values for the grade of mucosal villous atrophy, and (iii) aid diagnosing CD where minor histological changes are seen. DS can also provide additional information to assess the response to a gluten-free diet as marked increase of their activities occurs four weeks after commencing it. Various endogenous and exogenous factors affecting DS might also be relevant when considering investigating the role of DS in other conditions including noncoeliac gluten sensitivity and DS deficiencies.

Molecular pathogenicity of novel sucrase-isomaltase mutations found in congenital sucrase-isomaltase deficiency patients

BACKGROUND & AIMS

Congenital sucrase-isomaltase deficiency (CSID) is a genetic disorder associated with mutations in the sucrase-isomaltase (SI) gene. The diagnosis of congenital diarrheal disorders like CSID is difficult due to unspecific symptoms and usually requires invasive biopsy sampling of the intestine. Sequencing of the SI gene and molecular analysis of the resulting potentially pathogenic SI protein variants may facilitate a diagnosis in the future. This study aimed to categorize SI mutations based on their functional consequences.

METHODS

cDNAs encoding 13 SI mutants were expressed in COS-1 cells. The molecular pathogenicity of the resulting SI mutants was defined by analyzing their biosynthesis, cellular localization, structure and enzymatic functions.

RESULTS

Three biosynthetic phenotypes for the novel SI mutations were identified. The first biosynthetic phenotype was defined by mutants that are intracellularly transported in a fashion similar to wild type SI and with normal, but varying, levels of enzymatic activity. The second biosynthetic phenotype was defined by mutants with delayed maturation and trafficking kinetics and reduced activity. The third group of mutants is entirely transport incompetent and functionally inactive.

CONCLUSIONS

The current study unraveled CSID as a multifaceted malabsorption disorder that comprises three major classes of functional and trafficking mutants of SI and established a gradient of mild to severe functional deficits in the enzymatic functions of the enzyme.

GENERAL SIGNIFICANCE

This novel concept and the existence of mild consequences in a number of SI mutants strongly propose that CSID is an underdiagnosed and a more common intestinal disease than currently known.

An activating gucy2c mutation causes impaired contractility and fluid stagnation in the small bowel

OBJECTIVE

Familial GUCY2C diarrhoea syndrome (FGDS) is caused by an activating mutation in the GUCY2C gene encoding the receptor guanylate cyclase C in enterocytes. Activation leads to increased secretion of fluid into the intestinal lumen. Twenty percent of the patients have increased risk of Crohn's disease and intestinal obstruction (CD, 20%) and the condition resembles irritable bowel syndrome with diarrhoea. We aimed to describe fluid content, contractility, peristaltic activity and bowel wall thickness in the intestine in fasting FGDS patients, using ultrasound, with healthy volunteers serving as controls.

METHODS

Twenty-three patients with FGDS and 22 healthy controls (HC) were examined with a Logiq E9 scanner in a fasting state. Bowel wall thickness was measured and fluid-filled small bowel loops were counted using three-dimensional (3D) magnetic positioning navigation. The HC ingested 500 ml PEG solution, an electrolyte balanced, non-absorbable solution, in order to investigate the contractions of the small bowel.

RESULTS

The fasting 23 FGDS patients had significantly higher number of fluid-filled small bowel segments compared to 22 fasting HC, p < 0.001. A high number of non-occlusive contractions in the ileum was observed, which was significant when compared to HC after ingesting PEG solution, p < 0.016. An increase in intestinal wall thickness or other signs of CD were not observed.

CONCLUSIONS

FGDS is characterised by multiple, fluid-filled small bowel loops with incomplete contractions and fluid stagnation in fasting state. These findings may play a role in the increased risk of bowel obstruction as well as IBS-like symptoms observed in these patients.

Genetic analysis of Italian patients with congenital tufting enteropathy

BACKGROUND

Congenital tufting enteropathy (CTE), an inherited autosomal recessive rare disease, is a severe diarrhea of infancy which is clinically characterized by absence of inflammation and presence of intestinal villous atrophy. Mutations in the EpCAM gene were identified to cause CTE. Recent cases of syndromic tufting enteropathy harboring the SPINT2 (19q13.2) mutation were described.

METHODS

Four CTE Italian patients were clinically and immunohistochemically characterized. Direct DNA sequencing of EpCAM and SPINT2 genes was performed.

RESULTS

All patients were of Italian origin. Three different mutations were detected (p.Asp219Metfs*15, Tyr186Phefs*6 and p.Ile146Asn) in the EpCAM gene; one of them is novel (p.Ile146Asn). Two patients (P1 and P2) showed compound heterozygosity revealing two mutations in separate alleles. A third patient (P3) was heterozygous for only one novel EpCAM missense mutation (p.Ile146Asn). In a syndromic patient (P4), no deleterious EpCAM mutation was found. Additional SPINT2 mutational analysis was performed. P4 showed a homozygous SPINT2 mutation (p.Y163C). No SPINT2 mutation was found in P3. CLDN7 was also evaluated as a candidate gene by mutational screening in P3 but no mutation was identified.

CONCLUSION

This study presented a molecular characterization of CTE Italian patients, and identified three mutations in the EpCAM gene and one in the SPINT2 gene. One of EpCAM mutations was novel, therefore increasing the mutational spectrum of allelic variants of the EpCAM gene. Molecular analysis of the SPINT2 gene also allowed us to identify a SPINT2 substitution mutation (c.488A>G) recently found to be associated with syndromic CTE subjects.

Congenital intestinal diarrhoeal diseases: A diagnostic and therapeutic challenge

Congenital diarrhoeal disorders are a heterogeneous group of inherited malabsorptive or secretory diseases typically appearing in the first weeks of life, which may be triggered by the introduction of distinct nutrients. However, they may also be unrecognised for a while and triggered by exogenous factors later on. In principle, they can be clinically classified as osmotic, secretory or inflammatory diarrhoea. In recent years the disease-causing molecular defects of these congenital disorders have been identified. According to the underlying pathophysiology they can be classified into four main groups: 1) Defects of digestion, absorption and transport of nutrients or electrolytes 2) Defects of absorptive enterocyte differentiation or polarisation 3) Defects of the enteroendocrine cells 4) Defects of the immune system affecting the intestine. Here, we describe the clinical presentation of congenital intestinal diarrhoeal diseases, the diagnostic work-up and specific treatment aspects.

Congenital diarrhoeal disorders: advances in this evolving web of inherited enteropathies

Congenital diarrhoeal disorders (CDDs) represent an evolving web of rare chronic enteropathies, with a typical onset early in life. In many of these conditions, severe chronic diarrhoea represents the primary clinical manifestation, whereas in others diarrhoea is only a component of a more complex multi-organ or systemic disorder. Typically, within the first days of life, diarrhoea leads to a life-threatening condition highlighted by severe dehydration and serum electrolyte abnormalities. Thus, in the vast majority of cases appropriate therapy must be started immediately to prevent dehydration and long-term, sometimes severe, complications. The number of well-characterized disorders attributed to CDDs has gradually increased over the past several years, and many new genes have been identified and functionally related to CDDs, opening new diagnostic and therapeutic perspectives. Molecular analysis has changed the diagnostic scenario in CDDs, and led to a reduction in invasive and expensive procedures. Major advances have been made in terms of pathogenesis, enabling a better understanding not only of these rare conditions but also of more common diseases mechanisms.

Features of gastric and colonic mucosa in congenital enteropathies: a study in histology and immunohistochemistry

Congenital enteropathies comprise a constellation of rare clinicopathologic diagnoses characterized by intractable watery diarrhea and failure to thrive in infants. These diagnoses include, but are not limited to, tufting enteropathy (TE), microvillous inclusion disease (MID), and enteroendocrine cell dysgenesis (EED). Commonly, the diagnosis is based on identification of their characteristic histologic and/or ultrastructural features in small intestinal mucosa. In cases in which the changes in the small intestine are inconclusive or a small intestine biopsy is not performed, the diagnosis can be hampered or significantly delayed. We describe the histologic features and immunohistochemical staining patterns of gastric and colonic mucosa in patients with confirmed TE (3), MID (2), and EED (1). Specifically, focal epithelial tufts were found in the gastric mucosa of one TE patient and multifocally in the colonic mucosa of another. All TE patients showed complete loss of membranous epithelial EpCAM expression in gastric and colonic mucosa, characteristic of the diagnosis. Gastric biopsies were available in 1 patient with MID; this showed focal disruption of the gastric glandular architecture. Three colon biopsies and 1 resection from 2 patients with MID showed characteristic cytoplasmic vacuoles and periodic acid-Schiff/villin-positive cytoplasmic inclusions. Chromogranin stains showed complete absence of enteroendocrine cells within the colon and a normal distribution in the gastric mucosa of the EED patient. On the basis of our findings, we conclude that the characteristic histologic and immunohistochemical features associated with the small intestine can be confirmed within the gastric and/or colonic mucosa by careful histologic examination and immunohistochemistry.

[Intestinal failure and transplantation in microvillous inclusion disease]

INTRODUCTION

Microvillous inclusion disease is a rare autosomal recessive condition, characterized by severe secretory diarrhea that produces a permanent intestinal failure and dependency on parenteral nutrition. It usually begins in the neonatal period, and the only treatment at present is intestinal transplantation.

PATIENTS AND METHODS

A retrospective review was conducted on 6 patients (three males and three females) diagnosed with microvillous inclusion disease between 1998 and 2013.

RESULTS

All debuted in the first month of life, with a median age of three days (range, 3-30 days), and had secretory diarrhea dependent on parenteral nutrition, with fasting fecal volume of 150-200ml/kg/day. Light microscopy of duodenal biopsy samples showed varying degrees of villous atrophy without cryptic hyperplasia, accumulation of PAS positive material in the cytoplasm of enterocytes brush border, and anti-CD10 immunostaining was suggestive of intracytoplasmic inclusions. Diagnostic confirmation was performed with electron microscopy. Two of them had a genetic study, and showed mutations in MYO5B gene. Three died and three are alive; two of them with an intestinal transplantation and the third waiting for a multivisceral transplantation.

Evaluation of intestinal biopsies for pediatric enteropathy: a proposed immunohistochemical panel approach

Congenital enteropathies are rare disorders with significant clinical consequences; however, definitive diagnosis based on morphologic assessment of duodenal biopsies with routine stains alone is often impossible. To determine the role of immunohistochemistry (IHC) in the evaluation for microvillous inclusion disease, congenital tufting enteropathy (intestinal epithelial dysplasia), and enteroendocrine cell dysgenesis, a series of duodenal biopsies from 26 pediatric patients with chronic/intractable diarrhea was retrospectively reviewed. IHC stains for CD10, EpCAM, chromogranin, and villin were performed on all biopsies, and the results were correlated with hematoxylin and eosin and ultrastructural findings using electron microscopy, when available. Biopsies from 2 patients diagnosed with microvillous inclusion disease at the time of original biopsy demonstrated diffuse CD10-positive cytoplasmic inclusions within enterocytes and normal expression of EpCAM and chromogranin. Biopsies from 3 patients, including 2 siblings with confirmed EPCAM mutations, demonstrated complete loss of EpCAM expression and normal expression of CD10 and chromogranin; electron microscopic evaluation revealed characteristic ultrastructural findings of tufting enteropathy. Biopsies from 1 patient with a confirmed NEUROG3 mutation demonstrated an absence of intestinal enteroendocrine cells by chromogranin staining, consistent with enteroendocrine cell dysgenesis. Four patients' biopsies displayed nonspecific staining patterns for CD10 and/or EpCAM with normal expression of chromogranin, and 16 patients' biopsies exhibited normal expression for all 3 markers. Villin stains demonstrated heterogenous brush border labeling with nonspecific cytoplasmic reactivity, a pattern variably present throughout the biopsy series. In conclusion, the routine use of an IHC panel of CD10, EpCAM, and chromogranin is warranted in patients meeting specific age and/or clinical criteria, as the morphologic findings of congenital enteropathies may be subtle, focal, or inapparent on routine stains.

A novel familial mutation in the PCSK1 gene that alters the oxyanion hole residue of proprotein convertase 1/3 and impairs its enzymatic activity

Four siblings presented with congenital diarrhea and various endocrinopathies. Exome sequencing and homozygosity mapping identified five regions, comprising 337 protein-coding genes that were shared by three affected siblings. Exome sequencing identified a novel homozygous N309K mutation in the proprotein convertase subtilisin/kexin type 1 (PCSK1) gene, encoding the neuroendocrine convertase 1 precursor (PC1/3) which was recently reported as a cause of Congenital Diarrhea Disorder (CDD). The PCSK1 mutation affected the oxyanion hole transition state-stabilizing amino acid within the active site, which is critical for appropriate proprotein maturation and enzyme activity. Unexpectedly, the N309K mutant protein exhibited normal, though slowed, prodomain removal and was secreted from both HEK293 and Neuro2A cells. However, the secreted enzyme showed no catalytic activity, and was not processed into the 66 kDa form. We conclude that the N309K enzyme is able to cleave its own propeptide but is catalytically inert against in trans substrates, and that this variant accounts for the enteric and systemic endocrinopathies seen in this large consanguineous kindred.

Genotype-dependency of butyrate efficacy in children with congenital chloride diarrhea

Background

Congenital chloride diarrhea (CLD) is an autosomal recessive disorder characterized by life-long, severe diarrhea with intestinal Cl^- malabsorption. It results from a reduced activity of the down regulated in adenoma exchanger (DRA), due to mutations in the solute carrier family 26, member 3 (SLC26A3) gene. Currently available therapies are not able to limit the severity of diarrhea in CLD. Conflicting results have been reported on the therapeutic efficacy of oral butyrate.

Methods

We investigated the effect of oral butyrate (100 mg/kg/day) in seven CLD children with different SLC26A3 genotypes. Nasal epithelial cells were obtained to assess the effect of butyrate on the expression of the two main Cl^- transporters: DRA and putative anion transporter-1 (PAT-1).

Results

A variable clinical response to butyrate was observed regarding the stool pattern and fecal ion loss. The best response was observed in subjects with missense and deletion mutations. Variable response to butyrate was also observed on SLC26A3 (DRA) and SLC26A6 (PAT1) gene expression in nasal epithelial cells of CLD patients.

Conclusions

We demonstrate a genotype-dependency for butyrate therapeutic efficacy in CLD. The effect of butyrate is related in part on a different modulation of the expression of the two main apical membrane Cl^- exchangers of epithelial cells, members of the SLC26 anion family.

Trial registration

Australian New Zealand Clinical trial Registry ACTRN12613000450718.

Investigation of chronic diarrhoea in infancy

Diarrhoea in infants and young children is defined as >200g/day of stools, and occurs when there is an imbalance between intestinal fluids absorption and secretion. This may be caused by either a decreased absorption (osmotic diarrhoea) or an increased secretion (secretory diarrhoea). Chronic diarrhoea defines intestinal loss of water and electrolytes with increased stool frequency, reduced consistency and larger volume over more than 14days. This disorder in children shows a wide range of aetiologies depending on the age. The knowledge of common and rare aetiologies is important to optimize the diagnostic approach. A stepwise approach, starting with a comprehensive history, physical examination, inspection and collection of stool samples, helps to devise appropriate diagnostic and therapeutic management. In this article we discuss the pathophysiology, aetiology and possible approach to chronic diarrhoea in infancy.

Extraintestinal manifestations in an infant with microvillus inclusion disease: complications or features of the disease?

Microvillus inclusion disease (MVID), a rare severe congenital enteropathy characterized by intracytoplasmic microvillous inclusions and variable brush border atrophy on intestinal epithelial cells histology, is associated with defective synthesis or abnormal function of the motor protein myosin Vb encoded by the MYO5B gene. Although MYO5B gene is expressed in all epithelial tissues, it is unclear so far whether organs other than intestine are affected in MVID patients. We report a case of an infant with MVID who presented liver dysfunction, hematuria, and Pneumocystis jiroveci pneumonia during the course of the disease. It is discussed whether extraintestinal manifestations in this patient are secondary consequences of MVID or might be features of the disease associated with altered MYO5B function.

CONCLUSIONS

MVID is classically included in the differential diagnosis of congenital diarrhea of secretory type. Recent advances in our knowledge regarding the role of myosin Vb in the pathophysiology of MVID is expected to clarify the clinical spectrum of the disease and the possible primary involvement of organs other than intestine.

DGAT1 mutation is linked to a congenital diarrheal disorder

Congenital diarrheal disorders (CDDs) are a collection of rare, heterogeneous enteropathies with early onset and often severe outcomes. Here, we report a family of Ashkenazi Jewish descent, with 2 out of 3 children affected by CDD. Both affected children presented 3 days after birth with severe, intractable diarrhea. One child died from complications at age 17 months. The second child showed marked improvement, with resolution of most symptoms at 10 to 12 months of age. Using exome sequencing, we identified a rare splice site mutation in the DGAT1 gene and found that both affected children were homozygous carriers. Molecular analysis of the mutant allele indicated a total loss of function, with no detectable DGAT1 protein or activity produced. The precise cause of diarrhea is unknown, but we speculate that it relates to abnormal fat absorption and buildup of DGAT substrates in the intestinal mucosa. Our results identify DGAT1 loss-of-function mutations as a rare cause of CDDs. These findings prompt concern for DGAT1 inhibition in humans, which is being assessed for treating metabolic and other diseases.

Chronic diarrhoea in children

Chronic diarrhoea in children shows an age related spectrum. In infants and young children a major role is related to persistent intestinal infections, intolerance to specific nutrients such as cow's milk protein, and toddler's diarrhoea. In older children and adolescents, inflammatory bowel diseases are strongly increasing and nonspecific diarrhoea is also frequent. Coeliac disease is a major cause of diarrhoea throughout childhood. In neonates, congenital diarrhoea is a rare but severe syndrome that includes several highly complex diseases. In children, diagnosis should be based on noninvasive techniques. Endoscopy should be decided based on clinical criteria, but also driven by noninvasive tests to assess the digestive absorptive functions and intestinal inflammation. A stepwise approach may reduce the need of endoscopy, also in the light of its relatively limited diagnostic yield compared to adult patients. Treatment of chronic diarrhoea in children is also substantially different from what is generally done in adults and includes a major role for nutritional interventions. Therefore chronic diarrhoea in children is a complex age-specific disorder that requires an age-specific management that is in many aspects distinct from that in adults.