Microvillus inclusion disease associated with coarctation of the aorta and bicuspid aortic valve

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.

Myosin Vb is required for correct trafficking of N-cadherin and cardiac chamber ballooning

BACKGROUND

During heart morphogenesis, the cardiac chambers undergo ballooning: a process involving regionalized elongation of cardiomyocytes. Cardiomyocyte shape changes require reorganization of the actin cytoskeleton; however, the genetic regulation of this process is not well understood.

RESULTS

From a forward genetic screen, we identified the zebrafish uq ^23ks mutant which manifests chamber ballooning defects. Whole-genome sequencing-mapping identified a truncating mutation in the gene, myo5b. myo5b encodes an atypical myosin required for endosome recycling and, consistent with this, increased vesicles were observed in myo5b mutant cardiomyocytes. Expression of RFP-Rab11a (a recycling endosome marker) confirmed increased recycling endosomes in cardiomyocytes of myo5b mutants. To investigate potential cargo of MyoVb-associated vesicles, we examined the adherens junction protein, N-cadherin. N-cadherin appeared mispatterned at cell junctions, and an increase in the number of intracellular particles was also apparent. Co-localization with RFP-Rab11a confirmed increased N-cadherin-positive recycling endosomes, demonstrating N-cadherin trafficking is perturbed in myo5b mutants. Finally, phalloidin staining showed disorganized F-actin in myo5b cardiomyocytes, suggesting the cytoskeleton fails to remodel, obstructing chamber ballooning.

CONCLUSIONS

MyoVb is required for cardiomyocyte endosomal recycling and appropriate N-cadherin localization during the onset of chamber ballooning. Cardiomyocytes lacking MyoVb are unable to reorganize their actin cytoskeleton, resulting in failed chamber ballooning. Developmental Dynamics 248:284-295, 2019. © 2019 Wiley Periodicals, Inc.

[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.

Microvillous atrophy: atypical presentations

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.

Microvillus inclusion disease associated with necrotizing enterocolitis in a premature infant

Microvillus inclusion disease is one of the congenital diarrheal disorders characterized by the appearance of inclusion bodies on the intestinal epithelium. To date there are a few cases and also a few other associated finding reports related to this life-threatening disease in literature. In this report, we present a premature infant with microvillus inclusion disease that was associated with necrotizing enterocolitis. Thus, we should be aware of the appearance of necrotizing enterocolitis in patients with microvillus inclusion disease, especially when contributing factors are present.

An overview and online registry of microvillus inclusion disease patients and their MYO5B mutations

Microvillus inclusion disease (MVID) is one of the most severe congenital intestinal disorders and is characterized by neonatal secretory diarrhea and the inability to absorb nutrients from the intestinal lumen. MVID is associated with patient-, family-, and ancestry-unique mutations in the MYO5B gene, encoding the actin-based motor protein myosin Vb. Here, we review the MYO5B gene and all currently known MYO5B mutations and for the first time methodologically categorize these with regard to functional protein domains and recurrence in MYO7A associated with Usher syndrome and other myosins. We also review animal models for MVID and the latest data on functional studies related to the myosin Vb protein. To congregate existing and future information on MVID geno-/phenotypes and facilitate its quick and easy sharing among clinicians and researchers, we have constructed an online MOLGENIS-based international patient registry (www.MVID-central.org). This easily accessible database currently contains detailed information of 137 MVID patients together with reported clinical/phenotypic details and 41 unique MYO5B mutations, of which several unpublished. The future expansion and prospective nature of this registry is expected to improve disease diagnosis, prognosis, and genetic counseling.

Prenatal diagnosis of de novo partial trisomy 18p and partial monosomy 18q recurrent in a family with fatal aortic coarctation

Aortic coarctation is a life-threatening defect when it occurs with cardiorespiratory failure. Its genetic cause remains unknown. A woman was pregnant twice, both with male fetuses that had partial trisomy 18p, partial monosomy 18q, and aortic coarctation. The syndrome may relate to the aortic coarctation and pulmonary hypoplasia and is life-threatening. ArrayCGH analysis suggested a de novo 17.7 Mb deletion of chromosome 18q21.33→qter (58,413,193 bp to 76,116,029 bp) and a de novo 12.4 Mb duplication of chromosome 18pter→p11.21 (1,543 bp to 12,438,430 bp) at the telomeric end of chromosome 18. To the best of our knowledge, the present chromosomal breakpoint with rearrangement has not been previously described. This chromosome aberration may be responsible for this syndrome.