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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., (© 2021 Wiley Periodicals LLC.)

Microvillous inclusion disease (MVID), also known as congenital microvillus atrophy, was first described by Davidson et al. in 1978. Till date, only a handful of cases with MVID have been described in English literature. It is an autosomal recessive disorder with no sex predisposition and more commonly noted in countries with prevalent consanguineous marriages. These patients usually present with intractable secretory diarrhea in early days of life. The pathognomonic findings of MVID are villous atrophy along with the formation of intracellular microvillous inclusions on electron microscopy. Till date, no curative therapy exists, and prognosis mainly depends upon parenteral nutrition. Small bowel transplantation is one of the treatment options. Clinician and pathologist should consider the possibility of MVID in the differential diagnosis of chronic intractable diarrhea in an infant. Herein, authors are describing a case of intractable diarrhea with MVID phenotype diagnosed in a 3-mo-old male child who presented with intractable diarrhea in an outside hospital, and the diagnostic workup was performed by the authors on endoscopic biopsy sample.

Congenital diarrheas correspond to a severe and low frequency digestive disease, with a high mortality. They start a few days or months after birth, leading to intestinal insufficiency and dependence on parenteral nutrition. It must be highly suspected in newborns or infants with diarrhea and severe electrolyte disorders. The diagnosis is based on clinical, endoscopic, histologic and eventually genetic findings. Treatment is supportive with intensive correction of electrolyte imbalances as well as parenteral nutrition., Objective: To present a case report of congenital diarrhea identified as microvillous inclusion disease presenting in the neonatal period., Case Report: Male patient currently 3 years of age, son of consanguineous parents. At 10 days of age presents a severe secretory diarrhea, requiring treatment in a critical care unit and parenteral nutrition. Initially he also presented with Fanconi syndrome, which improved afterwards. The suspicion of congenital microvillous inclusion was confirmed later by optic and electronic microscopy, and inmunohistochemistry. A succesful evolution was later achieved maintaining home parenteral nutrition after discharge., Conclusion: We present the first known case in Chile of congenital diarrhea due to microvillous inclusión disease and his evolution.

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., (Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.)

Inherited MYO5B mutations have recently been associated with microvillus inclusion disease (MVID), an autosomal recessive syndrome characterized by intractable, life-threatening, watery diarrhea appearing shortly after birth. Characterization of the molecular mechanisms underlying this disease and development of novel therapeutic approaches is hampered by the lack of animal models. In this study we describe the phenotype of a novel mouse model with targeted inactivation of Myo5b. Myo5b knockout mice show perinatal mortality, diarrhea and the characteristic mislocalization of apical and basolateral plasma membrane markers in enterocytes. Moreover, in transmission electron preparations, we observed microvillus atrophy and the presence of microvillus inclusion bodies. Importantly, Myo5b knockout embryos at day 20 of gestation already display all these structural defects, indicating that they are tissue autonomous rather than secondary to environmental cues, such as the long-term absence of nutrients in the intestine. Myo5b knockout mice closely resemble the phenotype of MVID patients and constitute a useful model to further investigate the underlying molecular mechanism of this disease and to preclinically assess the efficacy of novel therapeutic approaches.

Objectives: Microvillous inclusion disease (MVID) is a cause of intractable diarrhea in infancy. In its classic form, the disease is characterized by a severe persistent watery diarrhea starting within the first days of life. Parenteral nutrition and small bowel transplantation are the only known treatments for the affected children. Histologically, periodic acid-Schiff (PAS) staining shows accumulation of periodic acid-Schiff-positive staining material along the apical pole of enterocytes, whereas transmission electron microscopy exhibits microvillus inclusion bodies within the cytoplasm of enterocytes with rarefied and shortened microvilli and secretory granules. The objective of this work was to explore clinical, morphological, and genetic findings in cases of MVID with unusual presentations., Methods: Clinical, histological, and genetic findings are reported for 8 cases of MVID with atypical presentation., Results: The diarrhea started after several months in 3 cases. It was usually less abundant and 3 patients were weaned off parenteral nutrition. None required intestinal transplantation. Three patients experienced malformations, dysmorphy, sensory disabilities, and severe mental retardation. One had a hydrocephaly. Three patients had a cholestasis with low γ-glutamyl transferase levels. Light microscopy showed histological abnormalities consistent with MVID in all of the cases, but the lesions were sometimes focal or delayed. Transmission electron microscopy retrieved some criteria of MVID in 4 patients. Finally, 6 patients were homozygotes or compound heterozygotes for MYO5B mutations., Conclusions: This study extends the spectrum of MVID to less severe clinical presentations.

Unlabelled: 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.