Intractable infant diarrhea associated with phenotypic abnormalities and immunodeficiency

Trichohepatoenteric Syndrome: A Report of Two Children From Bahrain With a Novel Mutation and a Literature Review

Trichohepatoenteric syndrome (THES) is a rare genetic disorder inherited in an autosomal recessive manner. THES primarily leads to neonatal enteropathy, typically manifesting as severe, persistent diarrhea, distinctive facial features such as frontal bossing and a broad flat nasal bridge, woolly and fragile hair, immunodeficiency resulting in recurrent infections, failure to thrive (FTT), and liver complications including fibrosis or cirrhosis. This multisystem disorder is linked to mutations in the tetratricopeptide repeat domain 37 (TTC37) gene, also known as superkiller complex (SKIC) protein 3, responsible for THES type 1, and the Ski2-like ribonucleic acid (RNA) helicase (SKIV2L) gene, also known as SKIC2, responsible for THES type 2. This case report describes two far-related pediatric patients from Bahrain diagnosed with THES type 1. Although both patients exhibited typical symptoms of this syndrome, the first patient had more severe symptoms. Diagnostic genetic evaluations confirmed THES. Patient 1 had three homozygous variants in the TTC37 gene, while Patient 2 had two variants in the same gene. Both of our patients had a novel homozygous variant. The treatment focused on supportive care and infection management. Despite these efforts, patients did not reach their growth potential. This report underscores the necessity for early identification of THES to facilitate appropriate management and genetic counseling.

Gastrointestinal system involvement in patients with primary immunodeficiency: a single center experience

AIM

Primary immunodeficiencies (PIDs) are a heterogeneous disorder group characterized by an impaired immune system, leading to an increased susceptibility to infections and a wide range of clinical manifestations, including gastrointestinal (GI) complications. This study aimed to assess the GI manifestations of PID patients and highlight the significance of atypical gastrointestinal symptoms in the early diagnosis of these patients.

METHODS

A retrospective analysis was conducted on pediatric patients diagnosed with PIDs at Selcuk University Medical Faculty from 2011 to 2021. The study focused on demographic data, clinical presentation, genetic mutations, and GI manifestations, including endoscopic evaluation. Patients were categorized according to the International Union of Immunological Societies (IUIS) PID classifications. Statistical analyses were performed to identify significant associations between PID types and GI manifestations.

RESULTS

The cohort comprised 101 patients, with 46% presenting with GI symptoms, including malnutrition and chronic diarrhea, as the most common findings. Primary antibody deficiency (PAD) emerged as the most prevalent PID with GI involvement, followed by combined immunodeficiencies (CID) with associated or syndromic features. Endoscopic evaluations revealed inflammatory bowel disease (IBD)-like colitis in a significant subgroup of patients. The analysis showed that some GI symptoms were more common in specific PID categories, highlighting the importance of early gastroenterological assessment in PID patients.

CONCLUSION

Recognition of common GI symptoms in pediatric patients with PIDs may facilitate early diagnosis and prompt multidisciplinary management, potentially improving patient outcomes. The study highlights the necessity of considering PIDs in diagnosing persistent or severe GI symptoms in children.

Improved long-term outcome of children with congenital diarrhea followed by an intestinal rehabilitation program

BACKGROUND

Long-term outcomes of congenital diarrheas and enteropathies (CODE) are poorly described. We evaluated the morbidity and mortality of children with CODE followed by an intestinal rehabilitation program (IRP) compared to children with short bowel syndrome (SBS).

METHODS

Matched case-control study of children with intestinal failure (IF) due to CODE (diagnosed between 2006 and 2020; N = 15) and SBS (N = 42), matched 1:3, based on age at diagnosis and duration of parenteral nutrition (PN). Nutritional status, growth, and IF-related complications were compared. Survival and enteral autonomy were compared to a nonmatched SBS cohort (N = 177).

RESULTS

Fifteen CODE patients (five males, median age 3.2 years) were followed for a median of 2.9 years. Eleven children were alive at the end of the follow-up, and two achieved enteral autonomy. The CODE group had higher median PN fluid and calorie requirements than their matched SBS controls at the end of the follow-up (83 vs. 45 mL/kg/day, p = 0.01; 54 vs. 30.5 kcal/kg/day, p < 0.01), but had similar rates of growth parameters, intestinal failure associated liver disease, central venous catheter complications and nephrocalcinosis. Kaplan-Meier analyses of 10-year survival and enteral autonomy were significantly lower in CODE patients compared to the nonmatched SBS population (60% vs. 89% and 30% vs. 87%, respectively; log-rank p < 0.008).

CONCLUSIONS

Despite higher PN needs in CODE, rates of IF complications were similar to matched children with SBS. Enteral autonomy and survival rates were lower in CODE patients. Treatment by IRP can mitigate IF-related complications and improve CODE patient's outcome.

Diet management in congenital diarrheas and enteropathies - general concepts and disease-specific approach, a narrative review

Congenital diarrheas and enteropathies (CODE) are a group of rare, heterogenous, monogenic disorders that lead to chronic diarrhea in infancy. Definitive treatment is rarely available, and supportive treatment is the mainstay. Nutritional management in the form of either specialized formulas, restrictive diet, or parenteral nutrition support in CODE with poor enteral tolerance is the cornerstone of CODE treatment and long-term growth. The evidence to support the use of specific diet regimens and nutritional approaches in most CODE disorders is limited due to the rarity of these diseases and the scant published clinical experience. The goal of this review was to create a comprehensive guide for nutritional management in CODE, based on the currently available literature, disease mechanism, and the PediCODE group experience. Enteral diet management in CODE can be divided into 3 distinct conceptual frameworks: nutrient elimination, nutrient supplementation, and generalized nutrient restriction. Response to nutrient elimination or supplementation can lead to resolution or significant improvement in the chronic diarrhea of CODE and resumption of normal growth. This pattern can be seen in CODE due to carbohydrate malabsorption, defects in fat absorption, and occasionally in electrolyte transport defects. In contrast, general diet restriction is mainly supportive. However, occasionally it allows parenteral nutrition weaning or reduction over time, mainly in enteroendocrine defects and rarely in epithelial trafficking and polarity defects. Further research is required to better elucidate the role of diet in the treatment of CODE and the appropriate diet management for each disease.

Expanding the phenotypic and genotypic characteristics of trichohepatoenteric syndrome: a report of eight patients from five unrelated families

BACKGROUND

Trichohepatoenteric syndrome (THES) is characterized by neonatal-onset intractable diarrhea. It often requires long-term total parenteral nutrition (TPN). In addition, other characteristic findings of the syndrome include growth retardation, facial dysmorphism, hair abnormalities, various immunological problems and other rare system findings. Two genes and their associated pathogenic variants have been associated with this syndrome: SKIC3 and SKIC2.

METHODS AND RESULTS

In this case series, the clinical findings and molecular analysis results of a total of 8 patients from 5 different families who presented with persistent diarrhea and were diagnosed with THES were shared. Pathogenic variants were detected in the SKIC3 gene in 6 of our patients and in the SKIC2 gene in 2 patients. It was planned to compare the clinical findings of our patients with other patients, together with literature data, and to present yet-undefined phenotypic features that may be related to THES. In our case series, in addition to our patients with a novel variant, patient number 2 had a dual phenotype (THES and Spondyloepimetaphyseal dysplasia, sponastrime type) that has not been reported yet. Delay in gross motor skills, mild cognitive impairment, radioulnar synostosis, osteoporosis, nephropathy and cystic lesions (renal and liver) were observed as unreported phenotypic findings.

CONCLUSIONS

We are expanding the clinical and molecular repertoire of the syndrome regarding patients diagnosed with THES. We recommend that the NGS (next-generation sequencing) multigene panel should be used as a diagnostic tool in cases with persistent diarrhea.

Chronic diarrhoea due to trichohepatoenteric syndrome (THES) in an infant

An infant was admitted with suspected postinfectious malabsorption with watery diarrhoea, fever and failure to thrive. She had dehydration, acute kidney injury and metabolic acidosis, which were corrected with intravenous fluids and managed with empiric antibiotics and prophylactic antifungals. She also developed Escherichia coli sepsis, meningitis and Candida skin infections during hospitalisation, which were treated according to the culture reports. Intrauterine growth restriction, woolly hair and a broad nasal bridge with chronic refractory diarrhoea prompted genetic testing to rule out syndromic diarrhoea. Whole-exome sequencing revealed a pathogenic compound heterozygous mutation causing trichohepatoenteric syndrome. She succumbed to severe infections at 80 days of life. The condition is rare, and no established guidelines or specific treatments exist; the focus is to promote optimal growth through parenteral nutrition, elemental formula and infection control. Early suspicion and molecular genetic testing can help reduce the time to diagnosis, treatment and genetic counselling.

Long term outcomes in children with trichohepatoenteric syndrome

Trichohepatoenteric syndrome (THES) is a rare autosomal recessive disorder caused by mutations in either TTC37 or SKIV2L, usually leading to congenital diarrhea as part of a multisystem disease. Here, we report on the natural history of the disease for the largest UK cohort of patients with THES from 1996 to 2020. We systematically reviewed the clinical records and pathological specimens of patients diagnosed with THES managed in a single tertiary pediatric gastroenterology unit. Between 1996 and 2020, 13 patients (7 female and 6 male) were diagnosed with THES either by mutation analysis or by clinical phenotype. Two patients died from complications of infection. All patients received parenteral nutrition (PN) of which six patients were weaned off PN. All patients had gastrointestinal tract inflammation on endoscopy. Almost half of the cohort were diagnosed with monogenic inflammatory bowel disease (IBD) by the age of 11 years, confirmed by endoscopic and histological findings. Protracted diarrhea causing intestinal failure improves with time in all patients with THES, but monogenic IBD develops in later childhood that is refractory to conventional IBD treatments. Respiratory issues contribute to significant morbidity and mortality, and good respiratory care is crucial to prevent comorbidity.

SKI complex: A multifaceted cytoplasmic RNA exosome cofactor in mRNA metabolism with links to disease, developmental processes, and antiviral responses

RNA stability and quality control are integral parts of gene expression regulation. A key factor shaping eukaryotic transcriptomes, mainly via 3'-5' exoribonucleolytic trimming or degradation of diverse transcripts in nuclear and cytoplasmic compartments, is the RNA exosome. Precise exosome targeting to various RNA molecules requires strict collaboration with specialized auxiliary factors, which facilitate interactions with its substrates. The predominant class of cytoplasmic RNA targeted by the exosome are protein-coding transcripts, which are carefully scrutinized for errors during translation. Normal, functional mRNAs are turned over following protein synthesis by the exosome or by Xrn1 5'-3'-exonuclease, acting in concert with Dcp1/2 decapping complex. In turn, aberrant transcripts are eliminated by dedicated surveillance pathways, triggered whenever ribosome translocation is impaired. Cytoplasmic 3'-5' mRNA decay and surveillance are dependent on the tight cooperation between the exosome and its evolutionary conserved co-factor-the SKI (superkiller) complex (SKIc). Here, we summarize recent findings from structural, biochemical, and functional studies of SKIc roles in controlling cytoplasmic RNA metabolism, including links to various cellular processes. Mechanism of SKIc action is illuminated by presentation of its spatial structure and details of its interactions with exosome and ribosome. Furthermore, contribution of SKIc and exosome to various mRNA decay pathways, usually converging on recycling of ribosomal subunits, is delineated. A crucial physiological role of SKIc is emphasized by describing association between its dysfunction and devastating human disease-a trichohepatoenteric syndrome (THES). Eventually, we discuss SKIc functions in the regulation of antiviral defense systems, cell signaling and developmental transitions, emerging from interdisciplinary investigations. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Turnover and Surveillance > Regulation of RNA Stability RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.

Case Report: A Novel Homozygous Frameshift Mutation of the SKIV2L Gene in a Trichohepatoenteric Syndrome Patient Presenting With Short Stature, Premature Ovarian Failure, and Osteoporosis

Background: Trichohepatoenteric syndrome (THES) is a rare Mendelian autosomal recessive genetic disease characterized by intractable diarrhea, woolly hair, facial abnormality, immune dysfunction, and intrauterine growth restriction. THES mutations are found in the TTC37 and SKIV2L genes, which encode two components of the human superkiller (SKI) complex.

Methods and results: We report one case of a 32-year-old woman of Chinese descent with THES, who was born with a low weight (2000 g). She had intractable diarrhea during the neonatal period and was allergic to cow’s milk and condensed milk, but did not require total parenteral nutrition. She experienced menarche at age 12 and amenorrhea at age 28. In May 2019, the patient presented with a left fibular head fracture and was diagnosed with osteoporosis. Genetic testing showed a novel mutation in exon1 [p.E5Afs∗37 (c.12_13del)] of SKIV2L, which is composed of 28 exons. After the diagnosis, hormone replacement therapy was prescribed, in addition to the routine calcium and vitamin D supplements.

Conclusion: This case expands the clinical characteristic and phenotype spectrum of THES, providing further understanding of SKIV2L and its autoimmune influence.

Histopathology of intestinal villi in neonatal and paediatric age: main features with clinical correlation - Part I

The neonatal and paediatric spectrum of small bowel disorders encompass a wide variety of conditions, ranging from food allergies to life-threatening surgical emergencies or life-long medical conditions and, as such, it comes with a whole set of diagnostic challenges for the non-paediatric pathologist. Histologic examination is a cornerstone of diagnosis in a large number of diseases and may still provide important diagnostic clues in the appropriate clinical context. In this review, divided in two sections, we aim to provide a comprehensive histopathological summary of paediatric small bowel alteration and their differential diagnoses with a reference to the main clinical aspects required for appropriate interpretation. Specifically, in this first part, we describe congenital and metabolic disorders, intestinal lymphangiectasia, immunodeficiencies, GVHD, and necrotising enterocolitis.

Congenital enteropathies involving defects in enterocyte structure or differentiation

Congenital enteropathies (CE) are a group of rare inherited diseases with a typical onset early in life. They involve defects in enterocyte structure or differentiation. They can cause a severe condition of intestinal failure (IF). The diagnostic approach is based first on clinical presentation (consanguinity, prenatal expression, polyhydramnios, early neonatal onset, aspect of stools, persistence at bowel rest, associated extra-digestive manifestations….) and histo-pathological analyses. These rare intestinal diseases cause protracted diarrhea that might resolve, for a few, with a dietetic approach. However, protracted or permanent IF may require long term parenteral nutrition and, in limited cases, intestinal transplantation. With the progresses in both clinical nutrition and genetics, many of these CE are nowadays associated with recognized gene mutations. It improved our knowledge and the understanding in the patho-physiology of these diseases, thus, leading potentially to therapeutic perspectives. These review cover most of the early onset CE and excludes the immune related diarrhea.

A Case of Mild Trichohepatoenteric Syndrome With New Variant Mutation in SKIV2L Gene: Case Report

Trichohepatoenteric syndrome (THES) is a rare autosomal recessive genetic disease characterized by severe early onset diarrhea, woolly and brittle hair, immunodeficiency, and liver disease. A mutation in either SKIV2L or TTC37 genes can cause the disease. We report a case of a 41-month-old girl who suffered from intractable watery diarrhea, hair abnormality, dysmorphic features, and poor weight gain. The diagnosis was made through whole-exome sequencing analysis. The analysis detected a new variant mutation (c.1201G > A) p. (Glu401Lys) in the SKIV2L gene. She was admitted once for poor weight gain and nasogastric tube (NGT) feeding, with which the patient showed improvement. She was discharged to go home on hypoallergenic baby formulas and a regular diet with improved weight gain.

Intestinal immunoregulation: lessons from human mendelian diseases

The mechanisms that maintain intestinal homeostasis despite constant exposure of the gut surface to multiple environmental antigens and to billions of microbes have been scrutinized over the past 20 years with the goals to gain basic knowledge, but also to elucidate the pathogenesis of inflammatory bowel diseases (IBD) and to identify therapeutic targets for these severe diseases. Considerable insight has been obtained from studies based on gene inactivation in mice as well as from genome wide screens for genetic variants predisposing to human IBD. These studies are, however, not sufficient to delineate which pathways play key nonredundant role in the human intestinal barrier and to hierarchize their respective contribution. Here, we intend to illustrate how such insight can be derived from the study of human Mendelian diseases, in which severe intestinal pathology results from single gene defects that impair epithelial and or hematopoietic immune cell functions. We suggest that these diseases offer the unique opportunity to study in depth the pathogenic mechanisms leading to perturbation of intestinal homeostasis in humans. Furthermore, molecular dissection of monogenic intestinal diseases highlights key pathways that might be druggable and therapeutically targeted in common forms of IBD.

Tricho-hepato-enteric syndrome: Retrospective multicenter experience in Saudi Arabia

BACKGROUND

Trichohepatoenteric syndrome (THES) is a very rare disorder that is characterized by intractable congenital diarrhea, woolly hair, intrauterine growth restriction, facial dysmorphism, and short stature. Our knowledge of THES is limited due to the small number of reported cases.

METHODS

Thirty patients diagnosed with THES, all molecularly confirmed by whole exome sequencing (WES) to have biallelic variants in TTC37 or SKIV2L, were included in the study. Clinical, biochemical, and nutritional phenotypes and outcome data were collected from all participants.

RESULTS

The median age of THES patients was 3.7 years (0.9-23 years). Diarrhea and malnutrition were the most common clinical features (100%). Other common features included hair abnormalities (96%), skin hyperpigmentation (87%), facial dysmorphic abnormalities (73%), psychomotor retardation (57%), and hepatic abnormalities (30%). Twenty-five patients required parenteral nutrition (83%) with a mean duration of 13.34 months, and nearly half were eventually weaned off. Parenteral nutrition was associated with a poor prognosis. The vast majority of cases (89.6%) had biallelic variants in SKIV2L, with biallelic variants in TTC37 accounting for the remaining cases. A total of seven variants were identified in TTC37 (n = 3) and SKIV2L (n = 4). The underlying genotype influenced some phenotypic aspects, especially liver involvement, which was more common in TTC37-related THES.

CONCLUSION

Our data helps define the natural history of THES and provide clinical management guidelines.

Expanding the clinical spectrum in trichohepatoenteric syndrome

Trichohepatoenteric syndrome (THES) is a very rare autosomal recessive genetic disorder, which is characterized by intractable diarrhea during infancy, dysmorphic features, immunodeficiency, and a failure to thrive. There are still significant difficulties for patients and clinicians in terms of the management of THES, even though its molecular basis has been uncovered in the last decade. In this article, we have presented two cases relating to siblings that have been diagnosed with the condition. Concerning one of the patients, we described a novel variation (c.2114 + 5G > A) in the TTC37 gene and a mild clinical course; meanwhile, the other one was clinically diagnosed with THES at 17 years of age, but they had seizures and died suddenly. These cases expand the spectrum of clinical findings in relation to THES.

A New Variant Mutation in SKIV2L Gene in Case of Trichohepatoenteric Syndrome

Trichohepatoenteric syndrome is an autosomal recessive genetic disease with an estimated prevalence of 1:100,000. The mutation of the disease is placed either in SKIV2L or TTC37 genes. The onset of presentation is variable, but symptoms usually start with intractable diarrhea associated with woolly hair abnormality, immune dysfunction, and sometimes hepatic abnormality. This case is of a 10-month-old girl who was born at 37 + 2 weeks due to symmetrical intrauterine growth restriction (IUGR), with a low birth weight (1320 g). It was noticed during her stay in NICU that she had excessive diarrhea on day 8. Gastroenterology suggested starting an extensively-hydrolyzed formula, but no improvement noticed. The multidisciplinary teams decided to order whole-exome sequencing analysis after excluding diarrhea causes. The analysis detected a new variant mutation (c.1297C > T) p. (Arg433Cys). To our knowledge, this is the first time detected in a homozygous state in the SKIV2L gene, as this variant mutation has not been described in any previous literature. Our case was managed mainly by total parenteral nutrition. The patient responded to the treatment appropriately.

Updates in Pediatric Congenital Enteropathies: Differential Diagnosis, Testing, and Genetics

Congenital enteropathies comprise a heterogeneous group of disorders typically resulting in severe diarrhea and intestinal failure. Recent advances in and more widespread application of genetic testing have allowed more accurate diagnosis of these entities as well as identification of new disorders, provided a deeper understanding of intestinal pathophysiology through genotype-phenotype correlations, and permitted the exploration of more specific therapies to diseases that have heretofore been resistant to conventional treatments. The therapeutic armamentarium for these disorders now includes intestinal and hematopoietic stem cell transplantation, specific targeted therapy, such as the use of interleukin-1 receptor antagonists and, in some cases, gene therapy. These considerations are particularly applicable to the group of disorders identified as "very-early onset inflammatory bowel disease" (VEO-IBD), for which a veritable explosion of knowledge has occurred in the last decade. The pathologist plays a crucial role in assisting in the diagnosis of these entities and in ruling out other disorders that enter into the differential diagnosis.

Gastrointestinal Disorders Associated with Primary Immunodeficiency Diseases

There are now 354 inborn errors of immunity (primary immunodeficiency diseases (PIDDs)) with 344 distinct molecular etiologies reported according to the International Union of Immunological Sciences (IUIS) (Clin Gastroenterol Hepatol 11: p. 1050-63, 2013, Semin Gastrointest Dis 8: p. 22-32, 1997, J Clin Immunol 38: p. 96-128, 2018). Using the IUIS document as a reference and cross-checking PubMed ( www.ncbi.nlm.nih.pubmed.gov ), we found that approximately one third of the 354 diseases of impaired immunity have a gastrointestinal component [J Clin Immunol 38: p. 96-128, 2018]. Often, the gastrointestinal symptomatology and pathology is the heralding sign of a PIDD; therefore, it is important to recognize patterns of disease which may manifest along the gastrointestinal tract as a more global derangement of immune function. As such, holistic consideration of immunity is warranted in patients with clinically significant gastrointestinal disease. Here, we discuss the manifold presentations and GI-specific complications of PIDDs which could lead patients to seek advice from a variety of clinician specialists. Often, patients with these medical problems will engage general pediatricians, surgeons, gastroenterologists, rheumatologists, and clinical immunologists among others. Following delineation of the presenting concern, accurate and often molecular diagnosis is imperative and a multi-disciplinary approach warranted for optimal management. In this review, we will summarize the current state of understanding of PIDD gastrointestinal disease involvement. We will do so by focusing upon gastrointestinal disease categories (i.e., inflammatory, diarrhea, nodular lymphoid hyperplasia, liver/biliary tract, structural disease, and oncologic disease) with an intent to aid the healthcare provider who may encounter a patient with an as-yet undiagnosed PIDD who presents initially with a gastrointestinal symptom, sign, or problem.

An RNA Metabolism and Surveillance Quartet in the Major Histocompatibility Complex

At the central region of the mammalian major histocompatibility complex (MHC) is a complement gene cluster that codes for constituents of complement C3 convertases (C2, factor B and C4). Complement activation drives the humoral effector functions for immune response. Sandwiched between the genes for serine proteinase factor B and anchor protein C4 are four less known but critically important genes coding for essential functions related to metabolism and surveillance of RNA during the transcriptional and translational processes of gene expression. These four genes are NELF-E (RD), SKIV2L (SKI2W), DXO (DOM3Z) and STK19 (RP1 or G11) and dubbed as NSDK. NELF-E is the subunit E of negative elongation factor responsible for promoter proximal pause of transcription. SKIV2L is the RNA helicase for cytoplasmic exosomes responsible for degradation of de-polyadenylated mRNA and viral RNA. DXO is a powerful enzyme with pyro-phosphohydrolase activity towards 5' triphosphorylated RNA, decapping and exoribonuclease activities of faulty nuclear RNA molecules. STK19 is a nuclear kinase that phosphorylates RNA-binding proteins during transcription. STK19 is also involved in DNA repair during active transcription and in nuclear signal transduction. The genetic, biochemical and functional properties for NSDK in the MHC largely stay as a secret for many immunologists. Here we briefly review the roles of (a) NELF-E on transcriptional pausing; (b) SKIV2L on turnover of deadenylated or expired RNA 3'→5' through the Ski-exosome complex, and modulation of inflammatory response initiated by retinoic acid-inducible gene 1-like receptor (RLR) sensing of viral infections; (c) DXO on quality control of RNA integrity through recognition of 5' caps and destruction of faulty adducts in 5'→3' fashion; and (d) STK19 on nuclear protein phosphorylations. There is compelling evidence that a dysregulation or a deficiency of a NSDK gene would cause a malignant, immunologic or digestive disease.

Trichohepatoenteric syndrome: A rare mutation in SKIV2L gene in the first Balkan reported case

Trichohepatoenteric syndrome or syndromic diarrhea is a rare and severe Mendelian autosomal recessive syndrome characterized by intractable diarrhea, facial and hair abnormalities, liver dysfunction, immunodeficiency and failure to thrive. It has been associated with mutations in TTC37 and SKIV2L genes, which encode proteins of the SKI complex that contributes to the cytosolic degradation of the messenger RNA by the cell's exosome. We report a case of a male infant who suffered from typical symptoms and signs of trichohepatoenteric syndrome without immunodeficiency. The patient's genetic testing showed a very rare mutation in SKIV2L gene's 25 exons (p.Glu1038 fs*7 (c.3112_3140del)). Even though our patient was provided with total parenteral nutrition from birth, the child's death in the third year of age highlights the severity of the disease and the poor prognosis of this particular type of genetic predisposition.

Combined Immunodeficiency in Patients With Trichohepatoenteric Syndrome

The syndromic diarrhea/trichohepatoenteric syndrome (SD/THE) is a rare and multi-system genetic disorder caused by mutation in SKIV2L or in TTC37, two genes encoding subunits of the putative human SKI complex involved in RNA degradation. The main features are intractable diarrhea of infancy, hair abnormalities, facial dysmorphism, and intrauterine growth restriction. Immunologically this syndrome is associated with a hypogammaglobulinemia leading to an immunoglobulin supplementation. Our immune evaluation of a large French cohort of SD/THE patient revealed several immunological defects. First, switched memory B lymphocytes count is very low. Second, IFN-γ production by T and NK cells is impaired and associated with a reduced degranulation of NK cells. Third, T cell proliferation was abnormal in 3/6 TTC37-mutated patients. These three patients present with severe EBV infection and a transient hemophagocytosis which may be related to these immunological defects. Moreover, an immunological screening of patients with clinical features of SD/THE could facilitate both diagnosis and therapeutic management of these patients.

Tricho-Hepato-Enteric Syndrome mutation update: Mutations spectrum of TTC37 and SKIV2L, clinical analysis and future prospects

Tricho-Hepato-Enteric syndrome (THES) is a very rare autosomal recessive syndromic enteropathy caused by mutations of either TTC37 or SKIV2L genes. Very little is known of these two gene products in mammals nor of the pathophysiology of the disease. Since the identification of the genes, we have set up the molecular diagnostic of THES in routine, gathering a large cohort with clinical and molecular data. Here, we report the phenotype and genotype analysis of this cohort together with an extensive literature review of THES cases worldwide, that is, 96 individuals harboring mutations in one gene or the other. We set up locus-specific databases for both genes and reviewed the type of mutation as well as their localization in the proteins. No hot spot is evidenced for any type of mutation. The phenotypic analysis was first made on the whole cohort but is limited due to heterogeneity in clinical descriptions. We then examined the lab diagnostic cohort in detail for clinical manifestations. For the first time, we are able to suggest that patients lacking SKIV2L seem more severely affected than those lacking TTC37, in terms of liver damage and prenatal growth impairment.

Clinical spectrum of woolly hair: indications for cerebral involvement

BACKGROUND

Woolly Hair is an uncommon congenital anomaly of the scalp hair presenting with strongly coiled hair involving a localized area of the scalp or covering the entire side and occurring in non-black people. Isolated or localized wooly hair is usually benign and is not related to other disorders and/or complications. On the contrary, the generalized type may be related to disorders and syndromes affecting heart, cutis, liver and gastrointestinal organs. Among the syndromes presenting with wooly hair, the most known are the Naxos syndrome, the Carvajal-Huerta syndrome, the wooly hair/hypotrichosis, the ectodermal dysplasia-skin fragility, the tricho-hepato-enteric syndrome.

CASE PRESENTATION

To our knowledge, no cases of wooly hair syndromes has been associated to neurologic involvement. Among the clinical notes of patients admitted in the Pediatric Units of the Catania University, we have selected four individuals presenting wooly hair, who showed different clinical features and course: case 1 presenting with a localized wooly hair type; case 2, member of a family affected by WH with autosomal dominant inheritance, not associated to complications; case 3, a wooly hair patient who displayed a progressive, severe form of Rasmussen's encephalitis with fatal evolution, and case 4, wooly hair associated to brain malformation and drug-resistant epilepsy.

CONCLUSIONS

With this report, we aim to underline the wide spectrum of clinical presentation of individuals with WH and in particular we wish to give an annotation on a possible association of WH with severe neurologic disorders.

Tricho-hepato-enteric syndrome with novel SKIV2L gene mutations: A case report

RATIONALE

Tricho-hepato-enteric syndrome (THES) is a rare disorder caused by mutations in the TTC37 or SKIV2L genes and characterized by chronic diarrhea, liver disease, hair abnormalities, and high mortality in early childhood due to severe infection or liver cirrhosis.

PATIENT CONCERNS

The patient is the second child of three siblings born to non-consanguineous healthy Japanese parents. She had intrauterine growth retardation and was delivered at 33 weeks of gestation due to placental abruption. She presented with watery diarrhea, elevated levels of liver enzymes, multiple episodes of recurrent bacterial infection, and mild mental retardation. She had facial dysmorphism, including prominent forehead and hypertelorism, and had woolly hair without trichorrhexis nodosa.

DIAGNOSIS

Clinical features led to consideration of THES. Novel compound heterozygous nonsense mutations, c.1420G>T (p.Q474*) and c.3262G>T (p.E1088*), in the SKIV2L gene were identified in the patient, and decreased levels of SKIV2L protein expression were revealed by flow cytometry and confirmed by western blot analysis using patient peripheral blood mononuclear cells (PBMCs).

INTERVENTIONS

Total parenteral nutrition was required from day 30 to day 100. Trimethoprim-sulfamethoxazole prophylaxis was started at the age of 7 years after multiple episodes of bacterial pneumonia and otitis media.

OUTCOMES

Chronic diarrhea persisted for more than 10 years, but the symptoms gradually improved with age. At the age of 13 years, she started a normal diet in combination with oral nutritional supplementation and her height and weight were just below the 3rd percentile for healthy individuals. She developed secondary sex characteristics, and menarche occurred at the age of 12 years. Facial dysmorphism, including prominent forehead and hypertelorism, and woolly hair without trichorrhexis nodosa became noticeable as she matured.

LESSONS

Physicians must be aware of THES when they encounter a patient with infantile diarrhea, hair abnormalities, immune deficiency, mental retardation, and liver disease. Moreover, flow cytometric detection of SKIV2L protein in PBMCs may facilitate early diagnosis.

Management of syndromic diarrhea/tricho-hepato-enteric syndrome: A review of the literature

Syndromic diarrhea/tricho-hepato-enteric syndrome (SD/THE) is a rare disease linked to the loss of function of either TTC37 or SKIV2L, two components of the SKI complex. It is characterized by a combination of 9 signs (intractable diarrhea, hair abnormalities, facial dysmorphism, immune abnormalities, IUGR/SGA, liver abnormalities, skin abnormalities, congenital heart defect and platelet abnormalities). We present a comprehensive review of the management of SD/THE and tested therapeutic regimens. A review of the literature was conducted in May 2017: 29 articles and 2 abstracts were included describing a total of 80 patients, of which 40 presented with mutations of TTC37, 14 of SKIV2L. Parenteral nutrition was used in the management of 83% of the patients and weaned in 44% (mean duration of 14.97 months). Immunoglobulins were used in 33 patients, but data on efficacy was reported for 6 patients with a diminution of infection (n = 3) or diarrhea reduction (n = 2). Antibiotics (n = 11) provided no efficacy. Steroids (n = 17) and immunosuppressant drugs (n = 13) were used with little efficacy and mostly in patients with IBD-like SD/THE. Hematopoietic stem cell transplantation (HSCT) was performed in 4 patients: 2 died, for one it corrected the immune defects but not the other features and for the last one, it provided only a partial improvement. Finally, no specific diet was effective except for some contradictory reports for elemental formula. In conclusion, the management of SD/THE mainly involves parenteral nutrition and immunoglobulin supplementation. Antibiotics, steroids, immunosuppressants, and HSCT are not recommended as principle treatments since there is no evidence of efficacy.

Exome sequencing identifies a novel TTC37 mutation in the first reported case of Trichohepatoenteric syndrome (THE-S) in South Africa

Background

Trichohepatoenteric syndrome (THE-S) or phenotypic diarrhoea of infancy is a rare autosomal recessive disorder characterised by severe infantile diarrhoea, facial dysmorphism, immunodeficiency and woolly hair. It was first described in 1982 in two infants with intractable diarrhoea, liver cirrhosis and abnormal hair structure on microscopy. We report on two siblings from a consanguineous family of Somali descent who, despite extensive clinical investigation, remained undiagnosed until their demise. The index patient died of fulminant cytomegalovirus pneumonitis at 3 months of age.

Methods

Whole exome sequencing (WES) was performed on a premortem DNA sample from the index case. Variants in a homozygous recessive state or compound heterozygous state were prioritized as potential candidate variants using TAPER™. Sanger sequencing was done to genotype the parents, unaffected sibling and a deceased sibling for the variant of interest.

Results

Exome sequencing identified a novel homozygous mutation (c.4507C > T, rs200067423) in TTC37 which was confirmed by Sanger sequencing in the index case. The identification of this mutation led to the diagnosis of THE-S in the proband and the same homozygous variant was confirmed in a male sibling who died 4 years earlier with severe chronic diarrhoea of infancy. The unaffected parents and sister were heterozygous for the identified variant.

Conclusions

WES permitted definitive genetic diagnosis despite an atypical presentation in the index case and suggests that severe infection, likely secondary to immunodeficiency, may be a presenting feature. In addition definitive molecular diagnosis allows for genetic counseling and future prenatal diagnosis, and demonstrates the value of WES for post-mortem diagnosis of disorders with a non-specific clinical presentation in which a Mendelian cause is suspected.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-017-0388-5) contains supplementary material, which is available to authorized users.

Novel mutations in SKIV2L and TTC37 genes in Malaysian children with trichohepatoenteric syndrome

Trichohepatoenteric syndrome (THES) is a rare autosomal recessive disorder that is classically associated with intractable diarrhea with an onset within the first few months of life. Herein, we investigated and reported novel mutations in two causal genes in 3 Malaysian cases. Genomic DNA was extracted from peripheral blood obtained from patients in two Malaysian Chinese families. The exons of SKIV2L and TTC37 genes were amplified and sequenced by bi-directional sequencing to identify the point mutations within the coding sequence. Three Chinese boys from two families with characteristic features and clinical course were diagnosed with THES. In family-1, two point mutations were identified in the SKIV2L gene (c.1891G>A and c.3187C>T). In family-2, a single-nucleotide duplication (c.3426dupA) was found in the TTC37 gene. These mutations cause the production of abnormal non-functional gene product leading to the clinical manifestations in the patients. We reported three point mutations, which have not been previously described in other patients with THES in SKIV2L and TTC37 genes, including one nonsense, one frameshift, and one missense mutations.

Identifying Mutations of the Tetratricopeptide Repeat Domain 37 (TTC37) Gene in Infants With Intractable Diarrhea and a Comparison of Asian and Non-Asian Phenotype and Genotype: A Global Case-report Study of a Well-Defined Syndrome With Immunodeficiency

Syndromic diarrhea/tricho-hepato-enteric syndrome (SD/THE) is a rare, autosomal recessive and severe bowel disorder mainly caused by mutations in the tetratricopeptide repeat domain 37 (TTC37) gene which act as heterotetrameric cofactors to enhance aberrant mRNAs decay. The phenotype and immune profiles of SD/THE overlap those of primary immunodeficiency diseases (PIDs). Neonates with intractable diarrhea underwent immunologic assessments including immunoglobulin levels, lymphocyte subsets, lymphocyte proliferation, superoxide production, and IL-10 signaling function. Candidate genes for PIDs predisposing to inflammatory bowel disease were sequencing in this study. Two neonates, born to nonconsanguineous parents, suffered from intractable diarrhea, recurrent infections, and massive hematemesis from esopharyngeal varices due to liver cirrhosis or accompanying Trichorrhexis nodosa that developed with age and thus guided the diagnosis of SD/THE compatible to TTC37 mutations (homozygous DelK1155H, Fs*2; heterozygous Y1169Ter and InsA1143, Fs*3). Their immunologic evaluation showed normal mitogen-stimulated lymphocyte proliferation, superoxide production, and IL-10 signaling, but low IgG levels, undetectable antibody to hepatitis B surface antigen and decreased antigen-stimulated lymphocyte proliferation. A PubMed search for bi-allelic TTC37 mutations and phenotypes were recorded in 14 Asian and 12 non-Asian cases. They had similar presentations of infantile onset refractory diarrhea, facial dysmorphism, hair anomalies, low IgG, low birth weight, and consanguinity. A higher incidence of heart anomalies (8/14 vs 2/12; P = 0.0344, Chi-square), nonsense mutations (19 in 28 alleles), and hot-spot mutations (W936Ter, 2779-2G>A, and Y1169Ter) were found in the Asian compared with the non-Asian patients. Despite immunoglobulin therapy in 20 of the patients, 4 died from liver cirrhosis and 1 died from sepsis. Patients of all ethnicities with SD/THE with the characteristic triad of T nodosa, hepatic cirrhosis, and intractable enteropathy have low IgG, poor vaccine response and/or decreased antigen-stimulated lymphocyte proliferation. This is now better classified into the subgroup of "well-defined syndromes with immunodeficiency" (the update termed as "combined immunodeficiencies with associated or syndromic features") than "predominantly antibody deficiencies" in the update PIDs classification, and requires optimal interventions.

Value of allohaemagglutinins in the diagnosis of a polysaccharide antibody deficiency

Polysaccharide antibody deficiency is characterized by a poor or absent antibody response after vaccination with an unconjugated pneumococcal polysaccharide vaccine. Allohaemagglutinins (AHA) are antibodies to A or B polysaccharide antigens on the red blood cells, and are often used as an additional or alternative measure to assess the polysaccharide antibody response. However, few studies have been conducted to establish the clinical significance of AHA. To investigate the value of AHA to diagnose a polysaccharide antibody deficiency, pneumococcal polysaccharide antibody titres and AHA were studied retrospectively in 180 subjects in whom both tests had been performed. Receiver operating characteristic curves for AHA versus the pneumococcal vaccine response as a marker for the anti-polysaccharide immune response revealed an area under the curve between 0·5 and 0·573. Sensitivity and specificity of AHA to detect a polysaccharide antibody deficiency, as diagnosed by vaccination response, were low (calculated for cut-off 1/4-1/32). In subjects with only low pneumococcal antibody response, the prevalence of bronchiectasis was significantly higher than in subjects with only low AHA (45·5 and 1·3%, respectively) or normal pneumococcal antibody response and AHA (2·4%). A logistic regression model showed that low pneumococcal antibody response but not AHA was associated with bronchiectasis (odds ratio 46·2). The results of this study do not support the routine use of AHA to assess the polysaccharide antibody response in patients with suspected immunodeficiency, but more studies are warranted to clarify the subject further.

Expanding phenotypic and allelic heterogeneity of tricho-hepato-enteric syndrome

Molecular genetics studies are of increasing importance in the diagnosis and classification of congenital diarrheal disorders. We describe the molecular genetic basis of tricho-hepato-enteric syndrome in patients from Saudi Arabia with novel mutations of SKIV2L (c.3559_3579del, p.1187_1193del) and TTC37 (C4102T, p.Q1368X). Interestingly, the congenital presence of café-au-lait spots and their distribution in the pelvis and lower limbs were a unique and consistent clinical feature of these patients and may aid differential diagnosis of congenital diarrheal disorders. This study expands allelic and phenotypic heterogeneity of syndromic diarrhea/tricho-hepato-enteric syndrome.

Novel TTC37 Mutations in a Patient with Immunodeficiency without Diarrhea: Extending the Phenotype of Trichohepatoenteric Syndrome

Unbiased genetic diagnosis has increasingly associated seemingly unrelated somatic and immunological phenotypes. We report a male infant who presented within the first year of life with physical growth impairment, feeding difficulties, hyperemesis without diarrhea, and abnormal hair findings suggestive of trichorrhexis nodosa. With advancing age, moderate global developmental delay, susceptibility to frequent viral illnesses, otitis media, and purulent conjunctivitis were identified. Because of the repeated infections, an immunological evaluation was pursued and identified impaired antibody memory responses following pneumococcal vaccine administration. Immunoglobulin replacement therapy and nutritional support were employed as mainstays of therapy. The child is now aged 12 years and still without diarrhea. Whole exome sequencing identified compound heterozygous mutations in the TTC37 gene, a known cause of the trichohepatoenteric syndrome (THES). This case extends the known phenotype of THES and defines a potential subset for inclusion as an immune overlap syndrome.

Syndromic (phenotypic) diarrhoea of infancy/tricho-hepato-enteric syndrome

OBJECTIVES

Syndromic diarrhoea/tricho-hepato-enteric syndrome (SD/THE) is a rare congenital syndrome. The main features are intractable diarrhoea of infancy, hair abnormalities, facial dysmorphism, intrauterine growth restriction and immune system abnormalities. It has been linked to abnormalities in two components of the putative human ski complex: SKIV2L and TTC37. The long-term outcome of this syndrome is still unknown. We aim to describe the long-term outcome, in the French cohort of patients born since 1992.

DESIGN

Review of the clinical and biological features of the 15 patients with SD/THE, followed in France and born between 1992 and 2010.

RESULTS

All patients presented typical SD/THE syndrome features, of intractable diarrhoea in infancy requiring parenteral nutrition, a facial dysmorphism with hair abnormalities, and immunological disorders. Half of them also had liver and skin abnormalities. Five children died, among which 3 died due to infections. Probabilities of survival according to the Kaplan-Meier method were 93.3%, 86.7%, 74.3 and 61.9%, respectively at 1 year, 5 years, 10 years and 15 years of age. 3/15 were weaned from parenteral nutrition (PN) with likelihood of weaning being 10% at 5 years and 40% at 10 years. At birth 80% were small for gestational age and the short stature persisted in 60%. Haemophagocytic syndrome was noted in 60% and mild mental retardation was present in 60%.

CONCLUSIONS

SD/THE is a rare disease with high morbidity and mortality. Management should be focused on nutrition and immunological defects.

Syndromic diarrhea/Tricho-hepato-enteric syndrome

Abstract

Syndromic diarrhea/Tricho-hepato-enteric syndrome (SD/THE) is a rare and severe bowel disorder caused by mutation in SKIV2L or in TTC37, 2 genes encoding subunits of the putative human SKI complex. The estimated prevalence is 1/1,000,000 births and the transmission is autosomal recessive. The classical form is characterized by 5 clinical signs: intractable diarrhea of infancy beginning in the first month of life, usually leading to failure to thrive and requiring parenteral nutrition; facial dysmorphism characterised by prominent forehead and cheeks, broad nasal root and hypertelorism; hair abnormalities described as woolly and easily removable; immune disorders resulting from defective antibody production; intrauterine growth restriction. The aetiology is a defect in TTC37, a TPR containing protein, or in the RNA helicase SKIV2L, both constituting the putative human ski complex. The ski complex is a heterotetrameric cofactor of the cytoplasmic RNA exosome which ensures aberrants mRNAs decay. The diagnosis SD/THE is initially based on clinical findings and confirmed by direct sequencing of TTC37 and SKIV2L. Differential diagnosis with the other causes of intractable diarrhea is easily performed by pathologic investigations. During their clinical course, most of the children require parenteral nutrition and often immunoglobulin supplementation. With time, some of them can be weaned off parenteral nutrition and immunoglobulin supplementation. The prognosis depends on the management and is largely related to the occurrence of parenteral nutrition complications or infections. Even with optimal management, most of the children seem to experience failure to thrive and final short stature. Mild mental retardation is observed in half of the cases.

Abstract in French

Les diarrhées syndromiques ou syndrome tricho-hepato-enterique (SD/THE) sont un syndrome rare et sévère dont l’incidence est estimée à 1 cas pour 1 million de naissances et la transmission autosomique récessive. La forme typique associe 5 signes cliniques: une diarrhée grave rebelle nécessitant dans la majorité des cas une nutrition parentérale du fait de la malnutrition, une dysmorphie avec un front large et bombé, une racine du nez large et un hypertélorisme, des anomalies des cheveux qui sont fragiles, cassants, incoiffables et qualifiés de « laineux », un retard de croissance intra utérine et des anomalies de l’immunité à type de déficit en immunoglobuline ou d’absence de réponse aux antigènes vaccinaux. Des anomalies de deux protéines peuvent être à l’origine du syndrome SD/THE: TTC37, une protéine à motif TPR et SKIV2L, une hélicase à ARN, toutes 2 étant des constituants du complexe SKI humain. Le complexe SKI est un co-facteur de l’exosome cytoplasmique qui assure la dégradation des ARN aberrants ou exogènes. Le diagnostic est d’abord clinique puis confirmé par le séquençage des gènes TTC37 et SKIV2L. Le diagnostic différentiel avec les autres formes de diarrhées intraitables est fait grâce aux analyses anatomopathologiques qui montrent dans les autres formes, des lésions spécifiques. La prise en charge clinique repose sur la nutrition parentérale et la supplémentation en immunoglobuline si nécessaire. Un certain nombre d’enfants peuvent être sevrés de la nutrition parentérale et des supplémentations en immunoglobulines. En cas d’atteinte hépatique, celle-ci peut être sévère et conduire au décès. Même avec une prise en charge optimale, les enfants présentent une petite taille et, dans la moitié des cas, un retard mental modéré.

Disease name/synonyms – Syndromic diarrhea – Phenotypic diarrhea – Tricho-hepato-enteric syndrome – Intractable diarrhea of infancy with facial dysmorphism – Trichorrhexis nodosa and cirrhosis – Neonatal hemochromatosis phenotype with intractable diarrhea and hair abnormalities – Intractable infant diarrhea associated with phenotypic abnormalities and immune deficiency- Syndromatic diarrhea. [ORPHA84064 MIM 222470 and MIM614602]. Possibly chronic diarrhea and skin hyperpigmentation.

Kongenitale Diarrhö

Im Folgenden werden die derzeit bekannten Transporterdefekte des Gastrointestinaltrakts beschrieben und in 2 Kategorien eingeteilt (Tab. 6.1): - solche, deren genetische Mutation bekannt ist, - jene, bei denen das verantwortliche Chromosom identifiziert wurde, das betroffene Gen aber noch nicht bekannt ist. Allen Krankheitsbezeichnungen gemeinsam ist die zuständige OMIM-Nummer, mit deren Hilfe die klinische und genetische Entität in ausführlicher Beschreibung in der oben genannten Datenbank im Internet abgerufen werden kann. Diese Art der Darstellung erleichtert es dem Leser, auch sehr seltene Krankheiten erwähnt zu finden und weiterführende Information zu erhalten.

Trichohepatoenteric syndrome: founder mutation in asian indians

Trichohepatoenteric syndrome (THES) is characterized by chronic diarrhea, dysmorphic facies and hair abnormalities. Hepatic involvement varies from no abnormality to cirrhosis and hemochromatosis. Recently, mutations in the tetratricopeptide repeat domain 37 (TTC37) gene were identified to cause THES. The c.2808G>A variation was suggested as a possible founder mutation among the South Asians. We further report 2 unrelated cases of Asian-Indian ethnicity (Gujrati) with THES, wherein targeted mutation analysis revealed the same mutation in homozygous form in both cases. These findings, as well as haplotype analysis, corroborate the founder mutation hypothesis amongst Asian Indo-Pakistani ethnic groups. A restriction enzyme-based method is also described to identify this founder mutation. One of our probands had multiple hepatic hemangiomas, a feature not previously observed in this syndrome.

SKIV2L mutations cause syndromic diarrhea, or trichohepatoenteric syndrome

Syndromic diarrhea (or trichohepatoenteric syndrome) is a rare congenital bowel disorder characterized by intractable diarrhea and woolly hair, and it has recently been associated with mutations in TTC37. Although databases report TTC37 as being the human ortholog of Ski3p, one of the yeast Ski-complex cofactors, this lead was not investigated in initial studies. The Ski complex is a multiprotein complex required for exosome-mediated RNA surveillance, including the regulation of normal mRNA and the decay of nonfunctional mRNA. Considering the fact that TTC37 is homologous to Ski3p, we explored a gene encoding another Ski-complex cofactor, SKIV2L, in six individuals presenting with typical syndromic diarrhea without variation in TTC37. We identified mutations in all six individuals. Our results show that mutations in genes encoding cofactors of the human Ski complex cause syndromic diarrhea, establishing a link between defects of the human exosome complex and a Mendelian disease.

Novel mutations in TTC37 associated with tricho-hepato-enteric syndrome

The Tricho-Hepato-Enteric (THE) syndrome is an autosomal recessive condition marked by early and intractable diarrhea, hair abnormalities, and immune defects. Mutations in TTC37, which encodes the putative protein Thespin, have recently been associated with THE syndrome. In this article, we extend the pattern of TTC37 mutations by the description of 11 novel mutations in 9 patients with a typical THE syndrome. The mutations were spread along the gene sequence, none of themrecurrent. Different types of mutation were observed: frameshift mutations, splice-site altering mutations, or missense mutations, most of them leading to the creation of a premature stop codon. Concurrently, we investigated the pattern of TTC37 expression in a panel of normal human tissues and showed that this gene is widely expressed, with high levels in vascular tissues, lymph node, pituitary, lung, and intestine. In contrast, TTC37 is not expressed in the liver, an organ that is not consistently affected in THE syndrome. Last, we suggested a model for the putative structure of the unknown Thespin protein.

Enteropathies of Infancy and Childhood

Intestinal biopsies constitute an ever-increasing portion of the pathologist's workload, accounting for nearly two-thirds of specimens accessioned yearly by the pathology department at The Children's Hospital of Philadelphia. The widespread use of endoscopy and gastrointestinal biopsies in current clinical practice presents the pathologist with a diversity of intestinal mucosal appearances corresponding to disease states of variable clinical severity, requiring close collaboration between clinician and pathologist for optimal interpretation. Many of the entities resulting in severe diarrhea of infancy have been recognized only in the last several decades, and although rare, the study of these disorders, especially when combined with the powerful methods of present-day genetics and molecular biology, has afforded important insights into enterocyte development and function, and intestinal immunity and tolerance. Other conditions once considered infrequent, such as celiac disease, have now been recognized to be much more common and can present with a wide range of pathologic features.

Mutations in TTC37 cause trichohepatoenteric syndrome (phenotypic diarrhea of infancy)

BACKGROUND & AIMS

Trichohepatoenteric syndrome (THES) is an autosomal-recessive disorder characterized by life-threatening diarrhea in infancy, immunodeficiency, liver disease, trichorrhexis nodosa, facial dysmorphism, hypopigmentation, and cardiac defects. We attempted to characterize the phenotype and elucidate the molecular basis of THES.

METHODS

Twelve patients with classic THES from 11 families had detailed phenotyping. Autozygosity mapping was undertaken in 8 patients from consanguineous families using 250,000 single nucleotide polymorphism arrays and linked regions evaluated using microsatellite markers. Linkage was confirmed to one region from which candidate genes were analyzed. The effect of mutations on protein production and/or localization in hepatocytes and intestinal epithelial cells from affected patients was characterized by immunohistochemistry.

RESULTS

Previously unrecognized platelet abnormalities (reduced platelet alpha-granules, unusual stimulated alpha granule content release, abnormal lipid inclusions, abnormal platelet canalicular system, and reduced number of microtubules) were identified. The THES locus was mapped to 5q14.3-5q21.2. Sequencing of candidate genes showed mutations in TTC37, which encodes the uncharacterized tetratricopeptide repeat protein, thespin. Bioinformatic analysis suggested thespin to be involved in protein-protein interactions or chaperone. Preliminary studies of enterocyte brush-border ion transporter proteins (sodium hydrogen exchanger 2, sodium hydrogen exchanger 3, aquaporin 7, sodium iodide symporter, and hydrogen potassium adenosine triphosphatase [ATPase]) showed reduced expression or mislocalization in all THES patients with different profiles for each. In contrast the basolateral localization of Na/K ATPase was not altered.

CONCLUSIONS

THES is caused by mutations in TTC37. TTC37 mutations have a multisystem effect, which may be owing to abnormal stability and/or intracellular localization of TTC37 target proteins.

Exclusion of EGFR, HRAS, DSP, JUP, CTNNB1, PLEC1, and EPPK1 as functional candidate genes in 7 families with syndromic diarrhoea

Syndromic diarrhoea (SD) is a rare disease associating intractable diarrhoea and hair abnormalities. In an attempt to identify the gene causative for SD, we studied several functional candidate genes, based on their implication in overlapping phenotypes in mice (EGFR) or in humans (HRAS, JUP, DSP EPPK1, PLEC1, and CTNNB1) in 8 patients affected by SD. Except for EGFR and HRAS, all selected genes encode for cell adhesion proteins. Using direct sequencing or linkage analysis, we excluded all of the candidate genes as the disease-causing gene in our group of patients; however, the hypothesis of intercellular junctions defect in SD remains seductive.

Genetic syndromic immunodeficiencies with antibody defects

This article reviews the major syndromic immunodeficiencies with significant antibody defects, many of which may require intravenous immunogammaglobulin therapy. The authors define syndromic immunodeficiency as an illness associated with a characteristic group of phenotypic abnormalities or laboratory features that comprise a recognizable syndrome. Many are familial with a defined inheritance pattern. Immunodeficiency may not be a major part of the illness and may not be present in all patients; thus, these conditions differ from primary immunodeficiency syndromes, in which immune abnormalities are a consistent and prominent feature of their disease.

Chronic diarrhea and skin hyperpigmentation: a new association

BACKGROUND/AIMS

The objective of this study was to describe patients with chronic diarrhea and abnormal skin hyperpigmentation with distinct distribution.

METHODS

This is a retrospective review of children who presented with diarrhea and skin hyperpigmentation. The clinical presentation, laboratory investigations as well as endoscopic and histological data were reviewed.

RESULTS

Seven patients with chronic diarrhea had abnormal skin hyperpigmentation with distinct distribution and presented in the first two months of life. Six patients had other features such as abnormal hair and facial dysmorphism. Mental retardation was reported in one patient. Consanguinity was positive in six patients, and there was family history of consanguinity in four patients, with two patients being siblings. No significant immunodeficiency was reported. Intestinal biopsies were obtained in six patients and showed active chronic inflammation in three patients, partial villous atrophy in two patients, and eosinophilic infiltrate with mild villous atrophy in one patient. Colonic biopsies showed mild focal colitis in three patients and mild colitis with eosinophilic infiltrate in one patient. Skin biopsies showed a greater number of melanophagies with fibrosis of papillary derma in two patients but skin biopsy was normal in one patient. The hair of two patients was analyzed by electron microscopy, which showed an abnormal pattern with decreased pigmentation and diameter; however, its chemical analysis was normal. Two other patients had trichorrhexis nodosa, but no abnormalities were seen in one patient. Chromosomal number was normal in three patients. One patient died because of sepsis, and only one patient was dependent on total parenteral nutrition.

CONCLUSIONS

We believe that this association might represent a new syndrome with an autosomal recessive inheritance that warrants further studies.

Syndromic (phenotypic) diarrhea in early infancy

Syndromic diarrhea (SD), also known as phenotypic diarrhea (PD) or tricho-hepato-enteric syndrome (THE), is a congenital enteropathy presenting with early-onset of severe diarrhea requiring parenteral nutrition (PN). To date, no epidemiological data are available. The estimated prevalence is approximately 1/300,000–400,000 live births in Western Europe. Ethnic origin does not appear to be associated with SD. Infants are born small for gestational age and present with facial dysmorphism including prominent forehead and cheeks, broad nasal root and hypertelorism. Hairs are woolly, easily removed and poorly pigmented. Severe and persistent diarrhea starts within the first 6 months of life (≤ 1 month in most cases) and is accompanied by severe malabsorption leading to early and relentless protein energy malnutrition with failure to thrive. Liver disease affects about half of patients with extensive fibrosis or cirrhosis. There is currently no specific biochemical profile, though a functional T-cell immune deficiency with defective antibody production was reported. Microscopic analysis of the hair show twisted hair (pili torti), aniso- and poilkilotrichosis, and trichorrhexis nodosa. Histopathological analysis of small intestine biopsy shows non-specific villous atrophy with low or no mononuclear cell infiltration of the lamina propria, and no specific histological abnormalities involving the epithelium. The etiology remains unknown. The frequent association of the disorder with parental consanguinity and/or affected siblings suggests a genetic origin with an autosomal recessive mode of transmission. Early management consists of total PN. Some infants have a rather milder phenotype with partial PN dependency or require only enteral feeding. Prognosis of this syndrome is poor, but most patients now survive, and about half of the patients may be weaned from PN at adolescence, but experience failure to thrive and final short stature.

Syndromic diarrhea – Phenotypic diarrhea – Tricho-hepato-enteric syndrome – Intractable diarrhea of infancy with facial dysmorphism – Trichorrhexis nodosa and cirrhosis – Neonatal hemochromatosis phenotype with intractable diarrhea and hair abnormalities – Intractable infant diarrhea associated with phenotypic abnormalities and immune deficiency.

A new syndrome of tufting enteropathy and choanal atresia, with ophthalmologic, hematologic and hair abnormalities

Three siblings are reported with a syndrome of intractable diarrhea of infancy (owing to tufting enteropathy) and choanal atresia/stenosis. Additional components of this condition are a mild shortness of stature, a prominent and broad nasal bridge, micrognathia, single palmar creases, chronic corneal inflammation, episodic cytopenia, and abnormal hair texture. Intelligence is normal, and there is no immunodeficiency distinguishing this syndrome from that reported by Girault et al. (1994). Additional features that might occur in this syndrome include bifid uvula, preauricular pits, and 2/3 toe syndactyly. We compare this syndrome with previously reported intractable diarrhea syndromes and speculate on the developmental mechanisms that could account for many of the features demonstrated by this sibship.

Intractable diarrhea with "phenotypic anomalies" and tricho-hepato-enteric syndrome: two names for the same disorder

Tricho-hepato-enteric syndrome and syndromic diarrhea are quite rare conditions with only 15 patients described to date. Both include severe diarrhea requiring total parenteral nutrition, facial dysmorphism, immunity defect, and hair abnormalities (mostly trichorrhexis nodosa). A definite clear clinical description of the two syndromes is lacking; the outcome is also poorly known. Here, we report on two additional patients. Analysis of our observations together with a review of previously published cases suggests that patients with tricho-hepato-enteric syndrome and/or syndromic diarrhea actually have the same heterogeneous disease that has been incorrectly and confusingly separated into different entities. The acknowledgment that these two syndromes represent the same disease is a crucial step toward a better description of this syndrome and its outcome toward studies of the underlying genetic cause.