Familial duodenal atresia: a report of two families and review

A Novel Use of Embryonic Gut Organoid Culture to Investigate Duodenal Atresia

BACKGROUND

The cause of duodenal atresia (DA) is not known. Tandler's "solid cord" hypothesis conflicts with current biological evidence. In humans, a genetic aetiology is supported by the association with Trisomy 21. Interruption of Fgf10 is the strongest genetic link to DA in mice, demonstrating an increased incidence and severity as embryos mature. This project aimed to develop an organoid model to facilitate ex vivo DA research on the FGF10/FGFR2b signalling pathway. We hypothesised that DA morphology represents an evolving spectrum of disease and that Fgf10 knockout organoids would vary in growth pattern compared to wild-type.

METHODS

Organoids were cultured from the duodenum of E12.5 Fgf10 knockout, heterozygous and wild-type embryos, using an air-liquid interface with Growth Factor reduced Matrigel. Organoids were photographed every 48 h to observe growth. Organoids were isolated and fixed after 14 days, then stained with DAPI, KI-67, and cytokeratin to demonstrate proliferation and differentiation.

RESULTS

Wild-type duodenum developed into crypt-forming organoids. Fgf10 heterozygous duodenum failed to progress beyond the development stage of spheroids. Fgf10 knockout duodenum failed to demonstrate any growth. Wholemount staining showed the greatest cell proliferation and differentiation in wild-type tissue.

CONCLUSION

This research presents a novel concept for the growth of embryonic gastrointestinal tissue to inform normal biology. The small sample numbers and restricted culture duration limit longer-term growth analysis. While this model serves as a potential ex vivo setting for future research, that research should consider organoid models with greater standardisation and other gastrointestinal regions.

LEVEL OF EVIDENCE

Animal/laboratory study.

Congenital duodenal obstruction - Advances in diagnosis, surgical management, and associated controversies

Congenital duodenal obstruction (CDO) occurs due to intrinsic and extrinsic mechanisms but is most often caused by intrinsic duodenal atresia and stenosis. This review will summarize the history, epidemiology, and etiologies associated with the most common causes of CDO. The clinical presentation, complex diagnostic considerations, and current surgical repair options for duodenal atresia and stenosis will also be discussed. Finally, both historical and recent controversies which continue to affect the surgical decision-making in the management of these patients will be highlighted.

The Role of Fibroblast Growth Factor 10 Signaling in Duodenal Atresia

Introduction

Duodenal atresia (DA) is a congenital bowel obstruction requiring major surgery in the first week of life. Three morphological phenotypes are described, reflecting increasing degrees of obstruction and discontinuity of the duodenum. The cause of DA is not known. Tandler’s original “solid cord” hypothesis conflicts with recent biological evidence, and is unable to account for differing DA types. In humans, a genetic etiology is supported by the association between Trisomy 21 and DA, and reports of familial inheritance patterns. Interruption of FGF10/FGFR2b signaling is the best demonstrated genetic link to DA in mice, with 35–75% of homozygous knockout embryos developing DA.

Purpose

This review examines the current evidence surrounding the etiology of DA. We focus on research regarding FGF10/FGFR2b signaling and its role in duodenal and other intestinal atresia. Further, we outline planned future research in this area, that we consider necessary to validate and better understand this murine model in order to successfully translate this research into clinical practice.

Conclusion

Determining the etiology of DA in humans is a clinical and scientific imperative. Fgf10/Fgfr2b murine models represent current science’s best key to unlocking this mystery. However, further research is required to understand the complex role of FGF10/FGFR2b signaling in DA development. Such complexity is expected, given the lethality of their associated defects makes ubiquitous interruption of either Fgf10 or Fgfr2b genes an unlikely cause of DA in humans. Rather, local or tissue-specific mutation in Fgf10, Fgfr2b, or their downstream targets, is the hypothesized basis of DA etiology.

Different types of intestinal atresia in identical twins

The authors present a previously unreported association of different types of intestinal atresia in identical low-birth-weight twins. Both babies were affected by duodenal atresia, associated in the first case with a complete mucosal duodenal membrane and in the second one with an "apple-peel" jejunal atresia. These occurrences may suggest that they were either the consequence of linkage of 2 genes or a pleiotropic expression of a single gene responsible for such rare conditions.

A proposed classification system for familial intestinal atresia and its relevance to the understanding of the etiology of jejunoileal atresia

Familial cases of the various types of intestinal atresia are well described, and we now report an additional family. Based on a review of the literature, a classification system for the different types of familial atresia is presented. Current teaching attributes most jejunoileal atresias to in utero vascular accidents occurring relatively late in gestation (after the 11th or 12th week). Although some cases clearly occur this way, as a result of processes such as volvulus and intussusception, knowledge of the familial form of the disease indicates that most cases of jejunoileal atresia actually result from disruption of a normal embryologic pathway, most likely the development of the superior mesenteric artery and its branches. They should be considered to be true embryologic malformations rather than acquired lesions.

The fibroblast growth factor pathway serves a regulatory role in proliferation and apoptosis in the pathogenesis of intestinal atresia

BACKGROUND/PURPOSE

Intestinal atresia occurs in 1:5000 live births and is a neonatal challenge. Fibroblast growth factor receptor 2b (Fgfr2b) is a critical developmental regulator of proliferation and apoptosis in multiple organ systems including the gastrointestinal tract (GIT). Fgfr2b invalidation results in an autosomal recessive intestinal atresia phenotype. This study evaluates the role of Fgfr2b signaling in regulating proliferation and apoptosis in the pathogenesis of intestinal atresia.

METHODS

Wild-type and Fgfr2b-/- embryos were harvested from timed pregnant mice. The GIT was harvested using standard techniques. Terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling) was used to evaluate apoptosis and bromodeoxyuridine to assess proliferation by standard protocols. Photomicrographs were compared (Institutional Animal Care and Use Committee-approved protocol 32-02).

RESULTS

Wild-type and mutant GIT demonstrate that deletion of the Fgfr2b gene results in inhibition of epithelial proliferation and increased apoptosis. Inhibited proliferation and increased apoptosis are specific to those tissues of normal Fgfr2b expression, corresponding to the site of intestinal atresia.

CONCLUSIONS

The absence of embryonic GIT Fgfr2b expression results in decreased proliferation and increased apoptosis resulting in GIT atresia. The regulation of proliferation and apoptosis in intestinal cells as a genetically based cause of intestinal atresia represents a novel consideration in the pathogenesis of intestinal atresia.

Double bubble, double trouble

Duodenal atresia (DA) is not uncommon, either as an isolated anomaly or associated with trisomy 21, malrotation, or cardiac anomalies. It may be diagnosed on antenatal ultrasound by a "double-bubble" sign, which typically persists after birth on a plain abdominal radiograph. DA as a familial association is rare but has been reported with or without other associated anomalies. We report DA in two siblings of nonconsanguineous parents, one case occurring with an annular pancreas in association with gestational diabetes. These two cases suggest possible genetic and environmental components in the aetiology of this anomaly.

Colonic atresia without mesenteric vascular occlusion. The role of the fibroblast growth factor 10 signaling pathway

BACKGROUND/PURPOSE

Colonic atresia occurs in 1:20,000 live births, offering a neonatal surgical challenge. Prenatal expression of fibroblast growth factor 10 (Fgf10), acting through fibroblast growth factor receptor 2b (Fgfr2b), is critical to the normal development of the colon. Invalidation of the Fgf10 pathway results in colonic atresia, inherited in an autosomal recessive pattern. Classically, disturbance of the mesenteric vasculature has been thought to cause many forms of intestinal atresia. The purpose of this study was to evaluate the role of vascular occlusion in the pathogenesis of colonic atresia.

METHODS

Wild type (Wt), Fgf10(-/-), and Fgfr2b(-/-) mutant mouse embryos were harvested from timed pregnant mothers. Immediately following harvest, filtered India ink was infused via intracardiac microinjection. The gastrointestinal tract was dissected, and photomicrographs of the mesenteric arterial anatomy were taken at key developmental time points.

RESULTS

Photomicrographs after India ink microinjections demonstrate normal, patent mesenteric cascades to the atretic colon at the time points corresponding to the failure of colonic development in the Fgf10(-/-) and Fgfr2b(-/-) mutants. The mesenteric arterial anatomy of the colon demonstrates no difference between the Wt and mutant colonic atresia.

CONCLUSIONS

The absence of embryonic expression of Fgf10 or its receptor Fgfr2b results in colonic atresia in mice. India ink microinjection is a direct measure of mesenteric arterial patency. Colonic atresia in the Fgf10(-/-) and Fgfr2b(-/-) mutants occurs despite normal mesenteric vascular development. Thus the atresia is not the result of a mesenteric vascular occlusion. The patent colonic mesentery of the Fgf10(-/-) and Fgfr2b(-/-) mutants challenges an accepted pathogenesis of intestinal atresia. Although colonic atresia can occur as a result of vascular occlusion, new evidence exists to suggest that a genetic mechanism may play a role in the pathogenesis of this disease.

A genetic mechanism for cecal atresia: the role of the Fgf10 signaling pathway

BACKGROUND

Intestinal atresia represents a significant surgically correctable cause of intestinal obstruction in neonates. Intestinal development proceeds as a tube-like structure with differentiation along its axis. As the intestine differentiates, the cecum develops at the transition from small to large intestine. Fgf10 is known to serve a key role in budding morphogenesis; however, little is known about its role in the development of this transitional structure. Here we evaluate the effect of Fgf10/Fgfr2b invalidation on the developing cecum.

MATERIALS AND METHODS

Wild-type C57Bl/6, Fgf10(-/-), and Fgfr2b(-/-) embryos harvested from timed pregnant mothers were analyzed for cecal phenotype, Fgf10 expression, and differentiation of smooth muscle actin.

RESULTS

Wt cecal development is first evident at E11.5. FGF10 is discreetly expressed in the area of the developing cecum at early stages of development. One hundred percent of Fgf10(-/-) and Fgfr2b(-/-) mutant embryos demonstrate cecal atresia with absence of epithelial and muscular layers. The development of neighboring anatomical structures such as the ileocecal valve is not affected by Fgf10/Fgfr2b invalidation.

CONCLUSIONS

FGF10 expression is localized to the cecum early in the normal development of the cecum. Fgf10(-/-) and Fgfr2b(-/-) mutant embryos demonstrate cecal atresia with complete penetrance. Epithelial and muscular layers of the cecum are not present in the atretic cecum. The Fgf10(-/-) and Fgfr2b(-/-) mutants represent a genetically reproducible animal model of autosomal recessive intestinal atresia.

Feingold syndrome: clinical review and genetic mapping

Feingold syndrome is characterized by autosomal dominant inheritance of microcephaly and limb malformations, notably hypoplastic thumbs, and clinodactyly of second and fifth fingers. Syndactyly frequently involves the second and third, as well as the fourth and fifth toes. Approximately one in three Feingold syndrome patients have esophageal or duodenal atresia or both. Anal atresia has been reported in a single case. At least 79 patients in 25 families have been reported. The syndrome has autosomal dominant inheritance with full penetrance, and variable expressivity. Vertebral anomalies, cardiac malformations, and deafness have been noted in a minority of patients. Here, we report a patient with hydronephrosis of one kidney and cystic dysplasia of the other, necessitating nephrectomy. The overall pattern of malformations in Feingold syndrome shows considerable overlap with the VATER/VACTERL association. The gene for Feingold syndrome maps to 2p23-p24, but remains to be identified. Comparison of the pattern of anomalies that occurs in the Feingold syndrome in humans and malformations that are present in mice with mutations of genes in the sonic hedgehog signaling pathway suggest, that the elusive Feingold syndrome gene may involve this signaling pathway as well.

Fibroblast growth factor receptor 2 IIIb invalidation--a potential cause of familial duodenal atresia

BACKGROUND/PURPOSE

Duodenal atresia (DA) occurs in 1 in every 6,000 live births and represents a significant surgically correctable cause of intestinal obstruction in the neonate. Familial or congenital DA has been reported, implying that at least some cases of DA are the result of genetic, heritable abnormalities. The genes controlling duodenal development are incompletely understood. Fibroblast growth factor receptor 2IIIb (Fgfr2b) is known to play a critical role in the development of multiple organ systems including other gastrointestinal tract (GIT) structures. This study shows the key role of Fgfr2b in normal duodenal development and the pathogenesis of DA.

METHODS

Wild type (Wt) and Fgfr2b-/- embryos were harvested from timed pregnant mothers at stage E18.5 and were analyzed for duodenal phenotype.

RESULTS

Inactivation of Fgfr2b results in DA. DA is present in the Fgf2b-/- mutants with a 35% penetrance. The duodenal phenotype of the Fgf2b-/- mutants ranges from normal to a mucosal web, type I, and type III atresia.

CONCLUSIONS

Fgfr2b is a critical regulatory gene in the development of the duodenum. Fgfr2b invalidation (Fgfr2b-/- mutant) results in a reproducible, autosomal recessive duodenal atresia phenotype with incomplete penetrance and a variable phenotype.

Junctional epidermolysis bullosa with pyloric atresia: A case with favourable outcome

BACKGROUND

Pyloric atresia is a rare but serious condition that can occur with junctional epidermolysis bullosa (PA-JEB). Early recognition is necessary for timely intervention, but prognosis can be serious and mortality is high.

OBJECTIVE

We describe the case of a patient with PA-JEB who not only survived past infancy, but showed improvement in cutaneous blistering as she grew older.

CONCLUSION

With early surgical intervention, some patients with PA-JEB can survive and look forward to a favourable prognosis, with improvement of cutaneous blistering by early childhood.

Duodenal atresia in dizygotic twins

The authors report duodenal atresia occurring in both members of dizygotic twins who showed no signs of Down's syndrome, and both had normal chromosomal constitutions. They both had the two unlinked end type of atresia in the second portion of the duodenum, and direct end-to-end duodenoduodenostomy was carried out. Their postoperative courses were smooth, and both babies were discharged 32 days after birth. Their mother underwent pituitary adenoma removal and partial parathyroidectomy for multiple endocrine neoplasia (MEN-type I). She had been given hormonal supplement therapy after surgery and became pregnant after exogenous gonadotropin therapy. Environmental factors may be responsible for some cases of duodenal atresia.

A familial disorder with duodenal atresia and tetralogy of Fallot

We report on two sibs with tetralogy of Fallot (TOF) and duodenal atresia (DA). The first child, a 6-year-old girl, had a right facial palsy in addition to the TOF and DA. Her brother, age 10 months, was born with bilateral microtia without facial palsy. The children are the product of an apparently non-consanguineous union between clinically normal parents. The pertinent family history includes a paternal aunt with TOF and a cleft lip and palate who died in childhood and another paternal aunt with a supernumerary thumb. This family has anomalies found in several syndromes, but does not meet the diagnostic criteria for any of them. The genetic basis for this condition remains unknown, but the pattern of inheritance is likely either autosomal recessive, or autosomal dominant with variable expression and reduced penetrance. The pathogenesis is unknown, but either a disturbance in neural crest cell migration or familial predisposition to vascular disruption might explain this pattern of malformations.

Immune deficiency in familial duodenal atresia

The familial occurrence of duodenal atresia is uncommon. This study evaluated the inheritance patterns, the nature and associations, and the presence of immunologic deficits in duodenal atresia recurring in at least three siblings each in two nonrelated families. In the first family, an association with Fanconi's anemia was observed in three of seven pregnancies (2 boys, 1 girl) suggesting an autosomal recessive mode of transmission. Patients died as a result of overwhelming (fungal) septicemia in association with pancytopenia. In a second family, identical multiple atresias occurred in two female siblings born 18 months apart and a third child with a duodenal stenosis. Overwhelming sepsis and a T-cell dysfunction was seen in the postoperative period, which had partially corrected by follow-up at 5 months. A history of family occurrence of duodenal atresia should alert the physician to the possibility of associated pathology including immune deficiency states.

Descriptive epidemiology of small intestinal atresia, Atlanta, Georgia

To describe the epidemiology of small intestinal atresia (SIA) in Atlanta, Georgia, from 1968 through 1989, we used the Metropolitan Atlanta Congenital Defects Program, an active, population-based surveillance system for birth defects diagnosed during the first year of life. We identified 176 infants with SIA, a prevalence of 2.8 per 10,000 livebirths. Among black infants, the prevalence was 3.7 per 10,000 livebirths, significantly higher than the prevalence of 2.4 per 10,000 among white infants [relative risk (RR) = 1.6, 95% confidence interval (CI) = 1.1,2.1]. Nine infants were each one member of a unique pair of twins. The prevalence among twin infants was 7.3 per 10,000, significantly higher than the prevalence of 2.8 per 10,000 among singletons (RR = 2.7, 95% CI = 1.4,5.2). Forty-nine percent of the infants had duodenal atresia, 36% had jejunal atresia, and 14% had ileal atresia. Two infants (1%) had atresia at an unspecified site in the small intestine. We grouped the infants by anatomic location of SIA into four categories: isolated SIA (53%), SIA with multiple unrelated defects (21%), sequences (16%), and syndromes (10%). We then compared the isolated and multiple unrelated defects groups by gender, race, maternal age, birth weight and one-year mortality for each location of SIA. Among black infants the prevalence of isolated jejunal atresia was 1.4 per 10,000, significantly higher than the prevalence of 0.2 per 10,000 among white infants (RR = 6.3, 95% CI = 2.9, 13.5). The increased prevalence of these defects among twins was a particularly interesting finding.

Autosomal dominant inheritance of abnormalities of the hands and feet with short palpebral fissures, variable microcephaly with learning disability, and oesophageal/duodenal atresia

We report two families with an autosomal dominant syndrome of abnormalities of the hands and feet, short palpebral fissures, and variable microcephaly with learning disability. Between a third and a quarter of cases are born with oesophageal atresia, duodenal atresia, or both. Individual patients have hypoplastic thumbs or congenital heart disease. The phenotype of the syndrome reported here is similar to that observed in 13q22-qter deletion patients. However, chromosome analysis has not detected any structural abnormality in our patients.