The epidemiology of extrahepatic biliary atresia in New York State, 1983-98

Biliary atresia

Biliary atresia (BA) is a progressive inflammatory fibrosclerosing disease of the biliary system and a major cause of neonatal cholestasis. It affects 1:5,000-20,000 live births, with the highest incidence in Asia. The pathogenesis is still unknown, but emerging research suggests a role for ciliary dysfunction, redox stress and hypoxia. The study of the underlying mechanisms can be conceptualized along the likely prenatal timing of an initial insult and the distinction between the injury and prenatal and postnatal responses to injury. Although still speculative, these emerging concepts, new diagnostic tools and early diagnosis might enable neoadjuvant therapy (possibly aimed at oxidative stress) before a Kasai portoenterostomy (KPE). This is particularly important, as timely KPE restores bile flow in only 50-75% of patients of whom many subsequently develop cholangitis, portal hypertension and progressive fibrosis; 60-75% of patients require liver transplantation by the age of 18 years. Early diagnosis, multidisciplinary management, centralization of surgery and optimized interventions for complications after KPE lead to better survival. Postoperative corticosteroid use has shown benefits, whereas the role of other adjuvant therapies remains to be evaluated. Continued research to better understand disease mechanisms is necessary to develop innovative treatments, including adjuvant therapies targeting the immune response, regenerative medicine approaches and new clinical tests to improve patient outcomes.

Incidence of Isolated Biliary Atresia during the COVID Lockdown in Europe: Results from a Collaborative Project by RARE-Liver

BACKGROUND

Biliary atresia (BA) is a rare cholangiopathy where one of the proposed aetiological mechanisms is an infectious viral trigger. Coronavirus disease-19 (COVID) lockdown restrictions were implemented to reduce the transmission of infections. Strictness of lockdown varied across European countries. This study aimed to investigate if there was an association between strictness of lockdown and change in isolated BA (IBA) incidence in Europe.

METHODS

We approached European centres involved in the European Reference Network RARE-LIVER. We included IBA patients born between 2015 and June 2020. We calculated the number of IBA patients born per centre per month. The Stringency Index (SI) was used as lockdown strictness indicator. The association between percentage change of mean number of IBA patients born per month and the SI was assessed.

RESULTS

We included 412 IBA patients from thirteen different centres. The median number of patients per month did not change: 6 (1-15) pre-lockdown and 7 (6-9) during lockdown (p = 0.34). There was an inverse association between SI and percentage change in IBA (B = -0.73, p = 0.03). Median age at Kasai portoenterostomy (days) did not differ between time periods (51 (9-179) vs. 53 (19-126), p = 0.73).

CONCLUSION

In this European study, a stricter COVID-lockdown was seemingly accompanied by a simultaneous larger decrease in the number of IBA patients born per month in the lockdown. Results should be interpreted with caution due to the assumptions and limitations of the analysis.

[Overview of Biliary Atresia]

Biliary atresia is a progressive, idiopathic, obliterative disease of the extrahepatic biliary tree that presents with biliary obstruction in the neonatal period. It is the most common indication for liver transplantation in children. If untreated, progressive liver cirrhosis leads to death by two years of age. Nowadays, more than 90% of biliary atresia patients survive into adulthood with the development of Kasai portoenterostomy and liver transplantation technology. Early diagnosis is critical since the success rate of the Kasai portoenterostomy decreases with time. This study comprehensively reviews the recent advances in the etiology, classification, prevalence, clinical manifestations, treatment, and prognosis of biliary atresia.

The Epidemiology of Biliary Atresia: Exploring the Role of Developmental Factors on Birth Prevalence

OBJECTIVE

To identify key epidemiologic factors relevant to fetal development that are associated with biliary atresia.

STUDY DESIGN

This population-based registry study examined infants born in Texas between 1999 and 2014. Epidemiologic data relevant to fetal development were compared between cases of biliary atresia identified in the Texas Birth Defects Registry (n = 305) vs all live births (n = 4 689 920), and Poisson regression was used to calculate prevalence ratios (PRs) and 95% CIs.

RESULTS

The prevalence of biliary atresia over the study period was 0.65 per 10 000 live births. Biliary atresia was positively associated with female sex (adjusted PR, 1.68; 95% CI, 1.33-2.12), delivery before 32-37 weeks of gestation (adjusted PR, 1.64; 95% CI, 1.18-2.29), delivery before 32 weeks of gestation (adjusted PR, 3.85; 95% CI, 2.38-6.22), and non-Hispanic Black vs non-Hispanic White maternal race/ethnicity (adjusted PR, 1.54, 95% CI, 1.06-2.24), while biliary atresia was inversely associated with season of conception in the fall relative to spring (adjusted PR, 0.62; 95% CI, 0.45-0.86). In addition, biliary atresia was associated with maternal diabetes (adjusted PR, 2.34; 95% CI, 1.57-3.48), with a stronger association with pregestational diabetes compared with gestational diabetes. In subgroup analyses, these associations were present in isolated biliary atresia cases that do not have any additional birth defects.

CONCLUSIONS

Biliary atresia is associated with multiple factors related to fetal development, including pregestational maternal diabetes, female sex, and preterm birth. These associations also were observed in isolated cases of biliary atresia without other malformations or laterality defects. Our results are consistent with early life events influencing the pathogenesis of biliary atresia, and support further studies investigating in utero events to better understand etiology and time of onset.

Portal plate bile duct diameter in biliary atresia is associated with long-term outcome

PURPOSE

Kasai portoenterostomy (KPE) is the only treatment currently available for biliary atresia (BA). Age at KPE and surgical experience are prognostic factors for a successful KPE. Here, we aimed to assess whether the size of bile ductules at the porta hepatis during KPE correlates with KPE success and transplant-free survival (TFS).

METHODS

A retrospective analysis of patients diagnosed with BA during 2000-2019. Porta hepatis biopsies were reviewed for diameters of five representative ducts, and a mean ductal diameter (MDD) was calculated. Laboratory values including pre- and postoperative bilirubin levels were analyzed.

RESULTS

The cohort included 77 patients; for 33, ductal plate biopsy was available. KPE was successful in six of eight patients with MDD ≥ 50 µm, and in five of 25 with MDD < 50 µm, p = 0.008, OR = 12.0 (95% CI 1.83-78.3). Ten-year survival with native liver was higher in patients with MDD ≥ 50 µm than in patients with MDD < 50 µm, p < 0.001, HR 0.038 (95% CI 0.007-0.207). Direct bilirubin < 1 mg/dl 3 months post-KPE was associated with improved 2-year post-KPE TFS (27.7% vs. 13.9%, p < 0.0001).

CONCLUSIONS

MDD ≥ 50 µm correlates with KPE success and a higher rate of TFS. Direct bilirubin < 1 mg/dl 3 months post-operation may serve as a marker of successful biliary excretion, and a predictor of 2-year TFS.

Current Understanding in the Clinical Characteristics and Molecular Mechanisms in Different Subtypes of Biliary Atresia

Biliary atresia is a severe obliterative cholangiopathy in early infancy that is by far the most common cause of surgical jaundice and the most common indicator for liver transplantation in children. With the advanced knowledge gained from different clinical trials and the development of research models, a more precise clinical classification of BA (i.e., isolated BA (IBA), cystic BA (CBA), syndromic BA (SBA), and cytomegalovirus-associated BA (CMVBA)) is proposed. Different BA subtypes have similar yet distinguishable clinical manifestations. The clinical and etiological heterogeneity leads to dramatically different prognoses; hence, treatment needs to be specific. In this study, we reviewed the clinical characteristics of different BA subtypes and revealed the molecular mechanisms of their developmental contributors. We aimed to highlight the differences among these various subtypes of BA which ultimately contribute to the development of a specific management protocol for each subtype.

Biliary Atresia in 2021: Epidemiology, Screening and Public Policy

Biliary atresia (BA) is a rare newborn liver disease with significant morbidity and mortality, especially if not recognized and treated early in life. It is the most common cause of liver-related death in children and the leading indication for liver transplantation in the pediatric population. Timely intervention with a Kasai portoenterostomy (KPE) can significantly improve prognosis. Delayed disease recognition, late patient referral, and untimely surgery remains a worldwide problem. This article will focus on biliary atresia from a global public health perspective, including disease epidemiology, current national screening programs, and their impact on outcome, as well as new and novel BA screening initiatives. Policy challenges for the implementation of BA screening programs will also be discussed, highlighting examples from the North American, European, and Asian experience.

Epidemiological characteristics and risk factors of biliary atresia: a case-control study

OBJECTIVES

Biliary atresia (BA) is regarded as a serious neonatal hepatobiliary disease, and its aetiology and pathogenesis remain unclear. Epidemiological studies are limited, especially for the data from China. This study aims to explore risk factors of BA and provide new evidence to improve understanding of its aetiology.

DESIGN

This is a case-control study from 1 January 2015 to 31 December 2016.

SETTING

Cases were consecutively recruited from an urban tertiary care academic children's hospital in Shanghai, China, while the controls were recruited from a community hospital in Shanghai through a random sampling system.

PARTICIPANTS

721 patients suspected for BA who planned to take the diagnostic surgery were enrolled preoperatively. 613 were diagnosed with BA and recruited into the case group. Meanwhile, 688 infants without any observed major congenital anomalies or jaundice were enrolled. Finally, 594 valid questionnaires from the case group and 681 from the control group were obtained.

PRIMARY AND SECONDARY OUTCOME MEASURES

Standardised questionnaires were used for data collection. Multivariate logistic regression analysis was performed to evaluate associations reported as ORs and precision, by adjusting covariates.

RESULTS

Anxiety or stress during pregnancy was strongly associated with increased risk of BA (OR 8.36 (95% CI: 4.08 to 17.15); p<0.001), respectively. Lower birth weight, fathers from ethnic minorities of China, older age of fathers, lower income of parents, and exposure to infection, diseases and medication during pregnancy all made differences.

CONCLUSIONS

Social factors including the educational and economic background and its related anxiety and stress during pregnancy might be noticed in the occurrence of BA. Maternal infections during pregnancy in the prevalence of BA were demonstrated.

TRIAL REGISTRATION NUMBER

ChiCTR-IPR-15005885.

Maternal mental disorders and risk of pathological abdominal conditions in children

The etiology of pediatric abdominal disorders is poorly understood, and the relationship with maternal mental health is understudied. We sought to determine the association between maternal psychiatric disorders and abdominal conditions in childhood. We performed a retrospective cohort study of 1,080,518 newborns in Quebec, Canada, between 2006 and 2020. We identified maternal mental disorders before or during pregnancy and computed the incidence of abdominal disorders in offspring before 1 year of age. Outcomes included Hirschsprung disease; hypertrophic pyloric stenosis; and esophageal, intestinal, and biliary atresia. We calculated adjusted risk ratios (RR) with 95% confidence intervals (CI) for the association of maternal mental disorders with these pediatric abdominal disorders. Among 51,371 children exposed to maternal mental disorders, 200 children had an abdominal condition, for a rate of 38.9 cases per 10,000 children (95% CI 33.6-44.3) compared with 27.7 per 10,000 for children who were unexposed to maternal mental disorders (95% CI 26.7-28.7). Compared with no mental disorder, maternal mental disorders were associated with hypertrophic pyloric stenosis (RR 1.39, 95% CI 1.16-1.68). Associations were stronger for severe mental disorders and were more marked for depression and stress and anxiety disorders. Maternal mental disorders are associated with the risk of hypertrophic pyloric stenosis in offspring. The origin of hypertrophic pyloric stenosis may relate to maternal mental disorders that were present during pregnancy.

A Higher Incidence of Isolated Biliary Atresia in Rural Areas: Results From an Epidemiological Study in The Netherlands

OBJECTIVES

Environmental factors may be involved in the pathogenesis of biliary atresia (BA). This epidemiological study aimed to analyze the relationships between the incidence of BA, the incidence of confirmed viral or bacterial infections and population density, and geographical and temporal clustering of BA in the Netherlands.

STUDY DESIGN

Correlations between the monthly incidence of BA and the number of confirmed infections were assessed. BA incidence per province was calculated and compared to the province with highest population density. Birthplaces were classified as rural or urban. Temporal clustering of month of birth and month of conception were analyzed. We performed analyses for isolated BA (IBA) and syndromic BA (SBA) separately. Chi2, logistic regression, and Walter and Elwood test were used.

RESULTS

A total of 262 IBA and 49 SBA patients, born between 1987 and 2018, were included. IBA incidence correlated to the number of confirmed infections of, for example, Chlamydia trachomatis (R = 0.14; P = 0.02) and adenovirus (R = 0.22; P = 0.005). We observed a higher incidence of IBA (0.75/10,000; odds ratio [OR] = 1.86; P = 0.04) and SBA (0.27/10,000; OR = 6.91; P = 0.001) in Groningen and a higher incidence of SBA in Gelderland (0.13/10,000; OR = 3.35; P = 0.03). IBA incidence was 68% higher in rural (0.67/10,000) versus urban areas (0.40/10,000) (P = 0.02). The estimated month of conception of patients with SBA clustered in November (85% increase compared to average SBA incidence [0.09/10,000; P = 0.04]).

CONCLUSIONS

IBA incidence correlated weakly with national confirmed infections. IBA and SBA incidence varied geographically in the Netherlands. IBA incidence was higher in rural than in urban areas, which may be explained decreased exposure to pathogens. Our results provide support for a role of environmental factors in the pathogenesis of IBA.

Biliary atresia: pathology, etiology and pathogenesis

Biliary atresia is a progressive fibrosing obstructive cholangiopathy of the intrahepatic and extrahepatic biliary system, resulting in obstruction of bile flow and neonatal jaundice. Histopathological findings in liver biopsies include the expansion of the portal tracts, with edematous fibroplasia and bile ductular proliferation, with bile plugs in duct lumen. Lobular morphological features may include variable multinucleate giant cells, bilirubinostasis and hemopoiesis. The etiopathogenesis of biliary atresia is multifactorial and multiple pathomechanisms have been proposed. Experimental and clinical studies have suggested that viral infection initiates biliary epithelium destruction and release of antigens that trigger a Th1 immune response, which leads to further injury of the bile duct, resulting in inflammation and obstructive scarring of the biliary tree. It has also been postulated that biliary atresia is caused by a defect in the normal remodelling process. Genetic predisposition has also been proposed as a factor for the development of biliary atresia.

Genome-wide association studies of structural birth defects: A review and commentary

BACKGROUND

While there is strong evidence that genetic risk factors play an important role in the etiologies of structural birth defects, compared to other diseases, there have been relatively few genome-wide association studies (GWAS) of these conditions. We reviewed the current landscape of GWAS conducted for birth defects, noting novel insights, and future directions.

METHODS

This article reviews the literature with regard to GWAS of structural birth defects. Key defects included in this review include oral clefts, congenital heart defects (CHDs), biliary atresia, pyloric stenosis, hypospadias, craniosynostosis, and clubfoot. Additionally, other issues related to GWAS are considered, including the assessment of polygenic risk scores and issues related to genetic ancestry, as well as utilizing genome-wide single nucleotide polymorphism array data to evaluate gene-environment interactions and Mendelian randomization.

RESULTS

For some birth defects, including oral clefts and CHDs, several novel susceptibility loci have been identified and replicated through GWAS, including 8q24 for oral clefts, DGKK for hypospadias, and 4p16 for CHDs. Relatively common birth defects for which there are currently no published GWAS include neural tube defects, anotia/microtia, anophthalmia/microphthalmia, gastroschisis, and omphalocele.

CONCLUSIONS

Overall, GWAS have been successful in identifying several novel susceptibility genes and genomic regions for structural birth defects. These findings have provided new insights into the etiologies of these phenotypes. However, GWAS have been underutilized for understanding the genetic etiologies of several birth defects.

Surgical modifications of the Kasai hepatoportoenterostomy minimize invasiveness without compromising short- and medium-term outcomes

BACKGROUND

Biliary atresia (BA) causes progressive fibrosis and obliteration of the biliary tree, resulting in bile stasis and eventual liver dysfunction. It affects 1 in 10,000-18,000 infants, and if left untreated, universally leads to liver failure. The Kasai hepatoportoenterostomy (KPE) was developed as an effective surgical therapy for BA and can restore bile drainage into the intestine. Traditionally, the KPE procedure extra-corporealizes the liver to expose the portal plate. Here, we describe modifications to the procedure via a smaller incision in which the liver remains within the abdominal cavity and we compare the outcomes of this technique to previous institutional outcomes and to contemporary international series.

MATERIALS AND METHODS

We identified all patients who underwent KPE for BA at a single institution between 1994 and 2012. Patient outcomes after the modified KPE performed from 2004 to 2012 were compared to data from infants who underwent the traditional KPE from 1994 to 2003.

RESULTS

Ninety-nine patients were identified. Fifty-two were in the traditional KPE group and 47 in the modified KPE group. There was no difference in mean age at surgery. Median follow-up was 64 months (traditional KPE) and 46 months (modified KPE). The rate of native liver survival (39.1% vs 48.5%), overall survival (89.2% vs 97.8%), liver transplant occurring under one year of age (36.5% vs 40.4%) and median time to liver transplant (188 vs 172 days) were not statistically different between groups (p > 0.05 for all comparisons). The results of the modified KPE compared favorably to published outcomes.

CONCLUSION

The described modifications to the KPE appear to yield equivalent outcomes when compared to the traditional KPE procedure and compare well with published outcomes in the literature. It is possible that the procedure described here results in less scarring and technically easier liver transplant procedures.

LEVEL OF EVIDENCE

Level III.

Genetic investigation into an increased susceptibility to biliary atresia in an extended New Zealand Māori family

Background

Biliary atresia (BA), a fibrosing disorder of the developing biliary tract leading to liver failure in infancy, has an elevated incidence in indigenous New Zealand (NZ) Māori. We investigated a high rate of BA in a group of children (n = 12) belonging to a single Māori iwi (or ‘tribe’, related through a remote ancestor).

Methods

Population and geographical data was used to estimate the rate of BA in Māori sub-groups, and a pedigree linking most of the affected children was constructed from oral and documented history. Array genotyping was used to examine hypotheses about the inheritance of a possible genetic risk factor, and the history of the affected population, and Exome Sequencing to search for candidate genes.

Results

Most of these affected children (n = 7) link to a self-reported pedigree and carry a 50-fold increase in BA risk over unrelated Māori (χ² = 296P < 0.001, 95% CI 23–111). Genetic analysis using FEstim and SNP array genotypes revealed no evidence for elevated consanguinity between parents of affected children (FEstim: F (2,21) = 0.469, P > 0.63). Genome-wide quantitation of intervals of contiguous, homozygous-by-state markers reached a similar conclusion (F (2,399) = 1.99, P = 0.138). Principal component analysis and investigation with STRUCTURE found no evidence of increased allele frequency of either a recessive variant, or additive, low-risk variants due to reproductive isolation. To identify candidate causal factors, Exome Sequencing datasets were scrutinised for shared rare coding variants across 8 affected individuals. No rare, non-synonymous, phylogenetically conserved variants were common to 6 or more affected children.

Conclusion

The substantially elevated risk for development of BA in this subgroup could be mediated by genetic factors, but the iwi exhibits no properties indicative of recent or remote reproductive isolation. Resolution of any risk loci may rely on extensive genomic sequencing studies in this iwi or investigation of other mechnaisms such as copy number variation.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0440-0) contains supplementary material, which is available to authorized users.

No association between month of birth and biliary atresia in a country with tropical climate

AIM

Children with biliary atresia (BA) born in countries with temperate climate showed month-of-birth (MoB) predilection during cooler months. To date, no study on the MoB-BA association has been performed in a tropical country. Our aim was to define MoB variation in children with BA in a tropical country.

METHODS

We studied 150 children diagnosed with BA between January 1996 and April 2015 at a teaching hospital. MoB was defined by two categories based on the precipitation: rain and dry, and three categories based on the air temperature: high, average and low. We applied the country's population data on the number of births in each period as the expected proportions of birth.

RESULTS

A slightly higher proportion of BA children was born in the rainy months (52.7%); however, the difference was not significant compared to the general population's birth (P = 0.87). For the MoB based on the air temperature, no statistically significant difference was noted. Males with BA seemed to have a greater MoB variation compared to females, but this did not reach statistical significance.

CONCLUSION

We could not find an association between MoB and BA in a tropical country. Multinational studies may aid in understanding the MoB-BA association in the tropical countries.

Factors Associated with Timing and Adverse Outcomes in Patients with Biliary Atresia Undergoing Kasai Hepatoportoenterostomy

OBJECTIVE

To assess factors associated with timing of hepatoportoenterostomy (HPE) and adverse perioperative outcomes in patients with biliary atresia in the US.

STUDY DESIGN

We examined hospitalizations in infants aged <1 year using the National Inpatient Sample database for 2000-2011. We identified cases using the International Classification of Diseases, Ninth Revision, Clinical Modification codes for biliary atresia and HPE. Multivariable logistic regression models were used to examine association between select factors and age at HPE, as well as adverse perioperative outcomes.

RESULTS

Our analysis of 1243 biliary atresia hospitalizations showed that only 37.7% of patients had HPE in the first 60 days of life. Patients who underwent HPE after 60 days of age were uninsured, were more likely to be black (aOR, 4.22; 95% CI, 1.49-11.95), less likely to be admitted at a teaching hospital (aOR, 0.27; 95% CI 0.10-0.79), and less likely to have a concomitant congenital malformation (aOR, 0.49; 95% CI 0.25-0.98). Patients with delayed age at HPE incurred significantly higher hospital costs ($57 914 vs $34 074; P = .026). Delayed age at HPE and weekend admission were independently associated with increased odds of adverse perioperative outcome (aOR, 1.09; 95% CI, 1.01-3.02 and 3.98; 95% CI, 1.67-9.46, respectively).

CONCLUSION

Current outcomes in patients with biliary atresia in the United States are suboptimal and result in higher costs. The specific factors associated with delayed care are further evidence that universal health care and screening are needed for all infants, along with systematic referral of potential patients with biliary atresia to specialized health centers.

Women's periconceptional diet and risk of biliary atresia in offspring

INTRODUCTION

We examined the association of biliary atresia with maternal dietary intake, using National Birth Defects Prevention Study (NBDPS) data from 152 cases and 11,112 nonmalformed controls born 1997-2011.

METHODS

NBDPS is a multisite, population-based case-control study. Exposure data were from maternal telephone interviews, which included a food frequency questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were generated from logistic regression models that included nutritional factors as continuous variables and were adjusted for energy intake only or energy intake plus covariates (maternal race-ethnicity, education, age, prepregnancy body mass index, vitamin/mineral supplement intake, conception during summer). Models included a quadratic term for the nutrient if p < 0.10. ORs reflect odds of having biliary atresia for nutrient values at the 75th compared to 25th percentile values of each nutrient, based on distributions among controls.

RESULTS

ORs for which the 95% CI excluded 1.00 were energy-adjusted ORs for calcium (0.63), protein (0.65), riboflavin (0.71), and diet quality index (0.69), and fully adjusted ORs for calcium (0.68) and vitamin E (0.72). ORs that were fully adjusted for covariates tended to be closer to 1.0 than ORs adjusted only for energy intake. ORs for the other studied nutrients had 95% CIs that included 1.00.

CONCLUSIONS

NBDPS is the first study to include detailed information on maternal dietary intake and risk of biliary atresia. Our results suggest reduced risks associated with some nutrients, which may provide etiologic clues but should be interpreted with caution given the small number of cases and novelty of the investigation.

Population-based birth defects data in the United States, 2010-2014: A focus on gastrointestinal defects

BACKGROUND

Gastrointestinal defects are a phenotypically and etiologically diverse group of malformations. Despite their combined prevalence and clinical impact, little is known about the epidemiology of these birth defects. Therefore, the objective of the 2017 National Birth Defects Prevention Network (NBDPN) data brief was to better describe the occurrence of gastrointestinal defects.

METHODS

As part of the 2017 NBDPN annual report, 28 state programs provided additional data on gastrointestinal defects for the period 2010-2014. Counts and prevalence estimates (per 10,000 live births) were calculated overall and by demographic characteristics for (1) biliary atresia; (2) esophageal atresia/tracheoesophageal fistula; (3) rectal and large intestinal atresia/stenosis; and (4) small intestinal atresia/stenosis. Additionally, we explored the frequency of these malformations co-occurring with other structural birth defects.

RESULTS

Pooling data from all participating registries, the prevalence estimates were: 0.7 per 10,000 live births for biliary atresia (713 cases); 2.3 per 10,000 live births for esophageal atresia/tracheoesophageal fistula (2,472 cases); 4.2 per 10,000 live births for rectal and large intestinal atresia/stenosis (4,334 cases); and 3.4 per 10,000 live births for small intestinal atresia/stenosis (3,388 cases). Findings related to co-occurring birth defects were especially notable for esophageal atresia/tracheoesophageal fistula, rectal and large intestinal atresia/stenosis, and small intestinal atresia/stenosis, where the median percentage of non-isolated cases was 53.9%, 45.5%, and 50.6%, respectively.

CONCLUSIONS

These population-based prevalence estimates confirm some previous studies, and provide a foundation for future epidemiologic studies of gastrointestinal defects. Exploring the genetic and environmental determinants of these malformations may yield new clues into their etiologies.

Preterm Infants With Biliary Atresia: A Nationwide Cohort Analysis From The Netherlands

OBJECTIVES

Biliary atresia (BA) occurs in 0.54 of 10.000 of overall live births in the Netherlands. BA has an unfavorable prognosis: <40% of patients are cleared of jaundice after Kasai portoenterostomy (KPE), 4-year transplant-free survival rate is 46% and the 4-year survival rate is ∼75%. Little is known on difficulties in diagnosis and the outcome of BA in preterm infants. We aimed to analyze the incidence and outcome of BA in preterm infants in the Netherlands.

METHODS

Retrospective study including Dutch preterm infants treated for BA. Parameters included gestational age, congenital anomalies, age at KPE, days between first symptoms, and KPE and referral interval (first hospital to KPE). Outcome parameters were clearance of jaundice (COJ) and (transplant-free) survival. Data are presented as medians (ranges).

RESULTS

Included 28 preterm infants (13 boys/15 girls) between March 1988 and December 2015. The incidence of BA was 1.06 of 10.000 preterm live births. Gestational age was 34.8 (27.3-36.9) weeks. Congenital anomalies were present in 11 of 28 (39%) infants. Time between first symptoms and KPE was 57 (9-138) days. Referral interval was 28 (8-86) days. Age at KPE was 70 (35-145) days. COJ was achieved in 23% of cases. Four-year transplant-free survival rate was 21%. Four-year overall survival was 61%.

CONCLUSIONS

BA has a higher incidence in the preterm population compared to the overall BA population. The outcome of BA in preterm infants is poor, regarding COJ and (transplant-free) survival. We speculate that timely recognition of BA-related signs and symptoms in preterm infants will improve prognosis.

Incidence of Biliary Atresia and Timing of Hepatoportoenterostomy in the United States

OBJECTIVE

To evaluate the incidence, trends, seasonality, and age at the time of hepatoportoenterostomy (Kasai procedure) for biliary atresia in the US.

STUDY DESIGN

The triennial Health Cost and Utilization Project-Kids' Inpatient Database for 1997-2012 was used to perform a retrospective analysis of biliary atresia in the US. Infants aged <1 year of age with a diagnosis of biliary atresia who underwent a Kasai procedure were included. Nationwide infant population data were used to calculate incidence and evaluate trends. Age at the time of the Kasai procedure and the seasonality of biliary atresia were evaluated as well.

RESULTS

The incidence of biliary atresia in the US was 4.47 per 100 000 and was higher in females (risk ratio [RR], 1.43; 95% CI, 1.27-1.62), Asian/Pacific Islanders (RR, 1.89; 95% CI, 1.44-2.47), and blacks (RR, 1.30; 95% CI, 1.06-1.58) compared with whites. The incidence of biliary atresia increased by an average of 7.9% per year from 1997 to 2012 (P <.001). The median age at the time of the Kasai procedure was 63 days, with no improvement over the study period (P = .64). There was no evidence of seasonality (P = .69).

CONCLUSION

The incidence of biliary atresia has increased over the past 15 years, with the median age at the time of the Kasai procedure now outside the optimal window. Implementation of systematic screening measures for biliary atresia in the US are needed.

Epidemiology of Biliary Atresia in Korea

Biliary atresia (BA) is the major cause of cholestasis and the leading indication for liver transplantation (LT). However, the incidence of BA in Korea has not been reported. The aim of this study was to investigate the incidence and clinical outcomes of BA in Korea. We used the Korean universal health insurance database and extracted data regarding BA patients younger than 18 years of age admitted between 2011 and 2015. The incidence of BA was calculated by dividing the number of BA patients by the number of live births. Two hundred forty infants were newly diagnosed with BA. A total of 963 BA patients younger than 18 years of age were followed up for 5 years. The overall incidence of BA was 1.06 cases per 10,000 live births. The incidence of BA was 1.4 times higher for female patients than for male patients. Additionally, significant seasonal variation was observed; in particular, the incidence of BA was 2 times higher from June through August than from December through February. Congenital anomalies were found in 38 of 240 patients (15.8%). Congenital heart diseases were major associated congenital anomalies (6.3%). Several complications developed during the study period, including cholangitis (24.0%), varix (6.2%), and gastrointestinal bleeding (4.4%). Three hundred and one of the 963 BA patients under 18 years of age (31.3%) received LT for BA. The incidence of BA is higher in Korea than that in Western countries. We also report significant gender-associated differences and seasonal variation with respect to the incidence of BA.

Prophylactic Antibiotics for Prevention of Cholangitis in Patients With Biliary Atresia Status Post-Kasai Portoenterostomy: A Systematic Review

PURPOSE

To determine effectiveness of prophylactic antibiotics in preventing cholangitis, we conducted a systematic review comparing cholangitis occurrence in biliary atresia patients after Kasai portoenterostomy (KP) with and without antibiotics.

METHODS

We searched online bibliographic databases from April 1, 2013, using search terms "biliary atresia" OR "cholangitis" AND "antibiotics," selecting studies with control group data.

RESULTS

Four of 509 titles met inclusion criteria, yielding a total of 319 patients from 3 countries. Three studies were retrospective cohorts and one was a randomized clinical trial. Two cohort studies concluded that prophylactic antibiotics reduced incidence of cholangitis and one did not. The randomized clinical trial supported prophylaxis after comparing the prospective randomized groups to a historical control group.

CONCLUSION

Few published studies measure the effect of prophylactic antibiotics after Kasai portoenterostomy. We identified 4 studies and they presented contradictory results. Prospective research is needed.

Genome-wide association studies in biliary atresia

Biliary atresia (BA) is a model complex disease resulting from interactions between multiple susceptibility loci and environmental factors. This perception is based on a heterogeneous phenotype extending beyond an absent extrahepatic bile duct to include gut and cardiovascular anomalies, and the association of BA with viral infections. Refractory jaundice and progression to cirrhosis shortly after birth can be fatal without surgical correction, and further suggests a pathogenesis during liver and bile duct development. Conclusive proof for a developmental origin would require documentation of disease progression in the perinatal or fetal liver, an impossible task for obvious reasons. We review three different sets of genome-wide association studies (GWAS) from three different cohorts of BA patients by three different groups of investigators, which address this knowledge gap. Knockdown of each susceptibility gene identified by GWAS in zebrafish embryos impairs excretion of bile from the liver, duplicating the characteristic diagnostic finding seen in affected children. This finding is associated with impaired intrahepatic biliary network formation in zebrafish morphants. Although distinct, these susceptibility genes share several functions including roles in mechanisms for organogenesis (glypican 1 or GPC1, and adenosine diphosphate ribosylation factor 6, or ARF6) or a greater expression in fetal liver than in adult liver (adducin 3 or ADD3). Together, these studies emphasize the importance of the human evidence, and present opportunities to map novel pathways which explain the phenotypic heterogeneity of BA.

Phenobarbital-enhanced hepatobiliary scintigraphy in the diagnosis of biliary atresia: two decades of experience at a tertiary center

BACKGROUND

Hepatobiliary scintigraphy is highly sensitive for diagnosing biliary atresia; however, its specificity has varied in the literature from 35% to 97%.

OBJECTIVE

The purpose of this study was to re-evaluate the accuracy of phenobarbital-enhanced hepatobiliary scintigraphy in differentiating biliary atresia from other causes of neonatal cholestasis.

MATERIALS AND METHODS

We retrospectively reviewed all hepatobiliary scans of infants with cholestasis at our institution from December 1990 to May 2011. Per our routine protocol the scans were obtained after pretreatment with phenobarbital (5 mg/kg/day for 5 days) to achieve a serum level of ≥15 mcg/ml. Normal hepatic uptake with no biliary excretion by 24 h was considered consistent with biliary atresia.

RESULTS

One hundred eighty-six infants with 210 hepatobiliary scans composed the study group. Forty-three (23%) infants had the final diagnosis of biliary atresia. Hepatobiliary scintigraphy was 100% sensitive, 93% specific and 94.6% accurate in diagnosing biliary atresia. Of the 186, 39/111 (35.1%) term and 2/68 (2.9%) preterm infants had biliary atresia; two of seven children with unknown gestational age also had biliary atresia. Other diagnoses included neonatal hepatitis, total parenteral nutrition cholestasis, Alagille syndrome, cystic fibrosis, choledochal cyst, hypothyroidism, alpha-1 antitrypsin deficiency and persistent cholestasis of unknown etiology.

CONCLUSION

Phenobarbital-enhanced hepatobiliary scintigraphy is highly accurate in differentiating biliary atresia from other causes of neonatal cholestasis. Biliary atresia is rare in premature infants.

Biliary atresia in preterm infants in Taiwan: a nationwide survey

OBJECTIVES

To investigate the characteristics of biliary atresia (BA) in preterm infants.

STUDY DESIGN

Nationwide screening for BA in Taiwan using an infant stool color card was launched in 2004. We investigated the characteristics of BA in preterm infants using the national stool card registry center database.

RESULTS

We identified 197 cases of BA from January 2004 to June 2010. The overall incidence of BA was 1.51 cases per 10,000 live births. The annual incidence of BA per 10,000 live births in term and preterm infants was 1.43 and 2.37 (P < .05), respectively. The sensitivity of detecting BA using stool cards before 60 days of age was 92.8% in term, and 96.3% in preterm infants. The Kasai operation before 60 days of age was 68.7% in term, and 44.4% in preterm infants. The jaundice-free rate at 3 months after the Kasai operation among infants with BA was 62.0% in term, and 37.0% in preterm infants (P = .015). The 18-month survival rate with native liver was higher in the term infants (72.7%) than that in the preterm infants (50.0%) (P = .043).

CONCLUSION

The incidence of BA in preterm infants is more frequent than in term infants. The stool color card is sensitive to detecting BA in preterm infants. Preterm infants with BA were more prone to delayed Kasai operation and had poorer outcome.

International incidence and outcomes of biliary atresia

OBJECTIVES

International trends in incidence and outcomes of biliary atresia (BA) are controversial and a wide range of estimates have been reported worldwide. We reviewed the population-based literature to assess international variation of BA incidence and outcomes, and to assess the evidence for seasonal variation in incidence, centralization of Kasai hepatoportoenterostomy, and newborn screening.

METHODS

We conducted a systematic review (registration number CRD42011001441) of observational or interventional research within MEDLINE, EMBASE, and the Cochrane Database, which reported incidence, prevalence, or outcomes of infants with BA. Population-based studies, defined by inclusion of an entire population or representative sample, were included. Outcomes included overall survival, native liver survival (NLS), and time to Kasai hepatoportoenterostomy. Single- or multicenter studies were excluded unless those centers captured all potential patients within a jurisdiction. Two independent data extractors reviewed the abstracts and articles.

RESULTS

A total of 40 studies were included following review of 3128 references. A wide range of incidence was reported internationally. Ten-year overall survival ranged from 66.7% to 89%. NLS ranged from 20.3% to 75.8% at 1 to 3 years and 24% to 52.8% at 10 years. Earlier age at Kasai was a predictor of improved NLS. Seasonality was reported in 11 studies, and 3 reported an increased incidence during the months of August to March. The evidence for centralization of Kasai to high-volume centers is promising but does not account for all case-mix, provider, or health system factors involved in volume-outcome relations. Stool color card screening resulted in earlier Kasai and improved NLS in Taiwan.

CONCLUSIONS

Large, international studies could help fill the gaps in knowledge identified by this review.

Early diagnosis of extrahepatic biliary atresia in an open-access medical system

Introduction

Biliary atresia (BA) is the most common cause of cholestatic jaundice in infancy. Early diagnosis and surgical management, ideally before 60 days of age, result in improved outcomes. We aimed to determine the age at diagnosis of BA in the Military Health System (MHS) and to compare the age at diagnosis by access to care models. We hypothesized that children with BA receiving primary care in military facilities have an earlier age at diagnosis due to decreased economic and access barriers.

Methods

Data for all Tricare enrollees born in fiscal years 2004–2008 with a diagnosis of BA were extracted from MHS databases. Non-parametric tests, Kaplan-Meier curves and log rank tests compared differences in age at diagnosis by type of primary care facility, gender, prematurity and presence of additional anomalies.

Results

64 subjects were identified within the five year period. Median age at diagnosis was 40 days [range 1–189], with 67% diagnosed by 60 days and 80% by 90 days. 45 (70%) received civilian primary care within the MHS. There was no difference in the median age at diagnosis between subjects in the MHS with civilian primary care vs. military primary care (37 days [1–188] vs. 46 days [1–189]; p = 0.58).

Conclusion

In the MHS, two-thirds of infants with biliary atresia are diagnosed prior to 60 days of life. Gender, prematurity or presence of additional anomalies do not affect the timing of diagnosis. Civilian and military primary care models within the MHS make timely diagnoses of biliary atresia at equivalent rates.

Biliary atresia: a multidisciplinary approach to diagnosis and management

CONTEXT

Biliary atresia is an inflammatory cholangiopathy of infancy that results in progressive fibrosis and obliteration of bile ducts and represents the main indication for liver transplant in young children. In spite of extensive investigation, its etiology has remained poorly understood. Timely surgical intervention (Kasai procedure) may result in significant benefit to these patients and represents the final goal of an accurate diagnostic evaluation.

OBJECTIVE

To present an overview of biliary atresia, including clinical and surgical approaches to this disease, with emphasis on the histopathologic evaluation.

DATA SOURCES

Review of relevant literature indexed in PubMed (US National Library of Medicine).

CONCLUSION

A well-coordinated multidisciplinary approach is required in the assessment of suspected cases of biliary atresia. Pathologic examination of biopsy specimens is an integral part of the diagnostic algorithm and, therefore, plays a pivotal role in the diagnostic evaluation of this disease.

Decreasing rate of biliary atresia in Taiwan: a survey, 2004-2009

OBJECTIVES

The pathogenesis of biliary atresia (BA) is unclear, but epidemiological studies may help to elucidate possible causes. The goals of this study were to identify BA incidence changes in Taiwan in 2004-2009 and to survey the factors that might influence incidence changes to elucidate the possible causes of BA.

METHODS

A Taiwan national registry system for BA has been established since 2004. By using data from the national registry system for BA, we identified BA incidence changes in 2004-2009. We also evaluated the correlations between BA incidences and estimated rotavirus vaccine coverage rates and between BA incidences and the gross domestic product.

RESULTS

A total of 185 patients with BA were identified in 2004-2009 in Taiwan, whereas the number of live births was 1 221 189. Compared with the incidence of BA in 2004-2006 (1.79 cases per 10,000 live births), the incidence of BA in 2007-2009 (1.23 cases per 10,000 live births) was decreased significantly (P = .01). BA incidences were negatively correlated with the gross domestic product (P = .02) and marginally negatively correlated with rotavirus vaccine coverage rates (P = .07).

CONCLUSIONS

A significant decrease in BA incidence in Taiwan since 2007 has been noted and may be related to improvements in the general socioeconomic status and the popularity of rotavirus vaccination. Although more evidence is needed to establish a direct correlation, this phenomenon may shed light on possible causes of and preventive interventions for BA.

Pseudo gallbladder sign in biliary atresia--an imaging pitfall

BACKGROUND

Ultrasound (US) is used to identify causes of neonatal cholestasis. We describe a potential sonographic pitfall, the "pseudo gallbladder," in biliary atresia (BA).

OBJECTIVE

To describe the Pseudo Gallbladder sign (PsGB sign).

MATERIALS AND METHODS

Sonograms/clinical records of 20 confirmed BA infants and 20 non-BA cases were reviewed retrospectively. For the BA group, preoperative sonography and surgical and pathological findings were examined. For the non-BA group, sonographic features and pathological findings were examined. The PsGB sign is defined as a fluid-filled structure, located in the expected region of the gallbladder, measuring ≤ 15 mm in length but without a well-defined or normal-appearing gallbladder wall.

RESULTS

A recognizable gallbladder and normal gallbladder wall were present in all non-BA infants. However, none of the BA infants had a sonographically normal gallbladder. Seventy-three percent of BA patients had a PsGB, and in 27% no gallbladder or gallbladder-like structure was detected.

CONCLUSION

A gallbladder-like structure in BA is common and can be misinterpreted as a normal gallbladder, delaying diagnosis and therapy. Recognition of this imaging pitfall, described here as the pseudo gallbladder sign, will help avoid this error.

Biliary atresia: the Croatian experience 1992-2006

The objective of this study was to determine the outcomes of Croatian children with biliary atresia. Health records of infants born in Croatia between January 1, 1992 and December 31, 2006 who were diagnosed with biliary atresia and treated at a single university center were reviewed. Survival rates were calculated with the Kaplan-Meier method. Twenty-nine patients with biliary atresia were identified. Incidence was one in 23,600 live births (95% confidence interval 1/17,400-1/27,200). The median age at Kasai operation was 66 days (range 22-192). Median follow-up was 2.65 years (range 0.2-14.3). Overall survival rates for the patients who underwent Kasai portoenterostomy, including those six (20%) who subsequently underwent liver transplantation, were 75.6%. Five and 10-year native liver survival rates were 51.7% and 38.8%, respectively (median survival time was 7.88 years). Survival rate curves in two groups of patients according to the biliary atresia phenotype (fetal or perinatal form) were divergent. Survival was 87.7% in perinatal form and 43.8% in fetal form (Breslow chi-square 8.082, p < 0.01). Overall survival rates of patients with biliary atresia in Croatia compared unfavorably with current international standards; this could be improved with earlier referral for liver transplantation. Results of Kasai operation (native liver survival rates) compared favorably with results reported elsewhere.

Trends in age for hepatoportoenterostomy in the United States

BACKGROUND

Biliary atresia is a rare but devastating disease for which hepatoportoenterostomy remains the primary intervention. Increased age at the time of hepatoportoenterostomy is associated with unfavorable outcomes. In this study, we examined trends in age at the time of hepatoportoenterostomy and explored hospital and patient factors associated with more timely diagnosis and treatment.

METHODS

Median ages of patients undergoing hepatoportoenterostomy for biliary atresia were compared using the Kids' Inpatients Database from 1997, 2000, 2003, and 2006. The patient and hospital factors associated with later treatment were compared.

RESULTS

Of 192 patients, 13.5% had surgery in 1997, 13.5% in 2000, 36.5% in 2003, and 36.5% in 2006. The overall median age was 65.5 days; the median age was 64 days in 1997, 57.5 days in 2000, 69 days in 2003, and 64 days in 2006 (P = .80). Overall, 71% of patients were treated at nonchildren's hospitals, and although the proportion has increased over time, the trend did not reach significance (P = .12). Hispanic and African American patients were more likely to undergo hepatoportoenterostomy after 60 days of life compared with white patients (Hispanic patients: odds ratio, 3.6; 95% confidence interval, 1.1-12.5; P = .04; African American patients: odds ratio, 2.2; 95% confidence interval, 0.8-6.3; P = .14). Compared with specialized children's centers, treatment at nonchildren's hospitals was associated with delayed hepatoportoenterostomy (odds ratio, 3.5; 95% confidence interval, 1.2-9.8; P = .02).

CONCLUSION

Although early hepatoportoenterostomy is associated with improved outcomes for children with biliary atresia, our study shows the median age at surgery has not significantly changed over 2 decades. Both hospital and socioeconomic factors play a role in the early treatment of biliary atresia.

Biliary atresia: service delivery and outcomes

Biliary atresia is a complex disorder dependent on multidisciplinary management. A series of comprehensive national audits in the United Kingdom and France exposed a clear relationship between center volume and clinical outcomes. Different models were adopted in each country in an attempt to improve results. In the United Kingdom, the management of biliary atresia was centralized to three specialist units in 1999, whereas in France, a strategy of decentralized management with closer inter-unit cooperation was adopted in 1997. Both policy changes led to improved outcomes for infants with biliary atresia, but only centralization improved the overall results of Kasai portoenterostomy. Other countries have adopted alternative systems of audit based on voluntary registries, but the impact of these on clinical outcomes at a national level remains unknown. The utility of monitoring tools in assessing performance in biliary atresia, the importance of risk stratification, and the need for standardized definitions of outcome are highlighted.

Epidemiological features of biliary atresia in Taiwan, a national study 1996-2003

BACKGROUND AND AIM

The incidence of biliary atresia (BA) varies among different countries. It is supposed to be higher in Asian countries than in Western countries; however, the incidence of BA in Taiwan has not been well investigated. The aim of this study was to analyze the epidemiological characteristics and the incidence of BA in Taiwan.

METHODS

National Health Insurance (NHI) was implemented in Taiwan in 1995, and covers most of the population (>99%). We use the NHI database to investigate the epidemiological features of BA and compare Taiwan's annual BA incidence with that of other countries.

RESULTS

We identified 327 new BA cases during the period from 1996 to 2003. The overall incidence of BA was 1.46 cases per 10 000 live births (0.89-1.90 per 10 000). The estimation was 1.32-1.65 per 10 000 after adjustment for the misdiagnosis rate. The peak incidence occurred in 2002 (1.90 per 10 000), accompanying Taiwan's dengue fever epidemic in 2002. The 5-year overall survival rate during 1999-2003 was higher than that during 1996-1998 (74.8% vs 61.1%, P = 0.014).

CONCLUSION

Taiwan has the second-highest incidence of BA reported in world literature. Viral infection outbreaks remain a potential candidate as a cause of BA. The management of BA has been improving, with a better 5-year overall survival rate.

Insignificant seasonal and geographical variation in incidence of biliary atresia in Japan: a regional survey of over 20 years

PURPOSE

Biliary atresia (BA) is the leading cause of obstructive jaundice in the newborn and the major indication for liver transplantation in Japan. Viral infection has been implicated in its etiology because of seasonality and space clustering. However, this has been controversial among whites. The present study investigates space-time clustering of the incidence of BA in Japan.

METHODS

Birth prevalence rates of BA were analyzed in infants born in Hyogo prefecture between 1985 and 2004 to assess time clustering among 3 seasons. The birth prevalence rates were also analyzed for space clustering between the northern (Hokkaido) and the southern islands (Kyushu) (difference of latitude, 10 degrees ) based on the Japanese Biliary Atresia Society Survey 1996-2004. We compared the prevalence rates between these groups using relative risks (RRs) calculated from 2 x 2 contingency tables.

RESULTS

One hundred nineteen infants were born with BA in Hyogo (1.1/10000 live births). Seasonal clustering in April to July did not significantly differ from that of the reference period (RR, 1.45; 95% confidence interval, 0.93-2.27). Based on Japanese registry data, space clustering between the northern and southern islands did not significantly differ (RR, 1.24; 95% confidence interval, 0.83-1.86).

CONCLUSIONS

Neither seasonal nor spatial clustering was statistically proven in Japan.

Screening and outcomes in biliary atresia: summary of a National Institutes of Health workshop

Biliary atresia is the most common cause of end-stage liver disease in the infant and is the leading pediatric indication for liver transplantation in the United States. Earlier diagnosis (<30-45 days of life) is associated with improved outcomes following the Kasai portoenterostomy and longer survival with the native liver. However, establishing this diagnosis is problematic because of its rarity, the much more common indirect hyperbilirubinemia that occurs in the newborn period, and the schedule for routine infant health care visits in the United States. The pathogenesis of biliary atresia appears to involve immune-mediated fibro-obliteration of the extrahepatic and intrahepatic biliary tree in most patients and defective morphogenesis of the biliary system in the remainder. The determinants of the outcome of portoenterostomy include the age at surgery, the center's experience, the presence of associated congenital anomalies, and the postoperative occurrence of cholangitis. A number of screening strategies in infants have been studied. The most promising are early measurements of serum conjugated bilirubin and a stool color card given to new parents that alerts them and their primary care provider to alcholic stools. This report summarizes a National Institutes of Health workshop held on September 12 and 13, 2006, in Bethesda, MD, that addressed the issues of outcomes, screening, and pathogenesis of biliary atresia.

Risk factors for isolated biliary atresia, National Birth Defects Prevention Study, 1997–2002

Biliary atresia is a rare birth defect that affects 1 in 12,000 to 1 in 19,500 live births. We used data from the National Birth Defects Prevention Study, a multistate case-control study, to identify potential risk factors for isolated biliary atresia (no additional unrelated major birth defects diagnosed). Infants were identified from eight states from 1997 to 2002, with clinical information abstracted from medical records. Potential risk factors assessed include: demographic factors, seasonality, preterm birth, maternal smoking, maternal alcohol use, maternal illicit drug use, maternal health, maternal medication use, maternal vitamin use, and maternal nutrition. Infants of non-Hispanic black mothers were more likely to have biliary atresia than infants of non-Hispanic white mothers (adjusted odds ratio (aOR) = 2.29, 95% confidence interval (CI) 1.07-4.93) and infants conceived during the spring season were more likely to have biliary atresia than infants conceived in winter (aOR = 2.33, 95%CI 1.05-5.16). Low intakes of vitamin E, copper, phosphorus, and beta tocopherol were associated with the occurrence of isolated biliary atresia (borderline significance). Low iron intake had a borderline inverse association with biliary atresia. While this analysis provides support for previous reports of a possible association between seasonal variation and the occurrence of biliary atresia, more data are needed to evaluate whether the seasonal variation is related to infectious agents. The role of nutrients in the development of biliary atresia remains unclear. Further studies of genetic, infectious, and nutrient exposures and the association of biliary atresia are warranted.

Pathogenesis and treatment opportunities for biliary atresia

Biliary atresia is the single most common cause of chronic cholestasis in children and is the leading indication for liver transplantation worldwide. It results from an inflammatory and fibrosing obstruction of the extrahepatic bile ducts in the first few months of life. Early diagnosis and timely surgical portoenterostomy are necessary for improved biliary drainage, but the liver disease progresses to end-stage biliary cirrhosis in most patients. Although the pathogenesis of disease is largely unknown, recent patient- and animal-based experiments indicate interactions between infectious agents and inflammatory circuits may be important pathogenic mechanisms of disease.

Unraveling the pathogenesis and etiology of biliary atresia

Biliary atresia (BA) is the most common and important neonatal hepatobiliary disorder. Because current treatment is inadequate, there is an urgent need to better understand the etiology and pathogenesis of BA. Two major forms of BA are recognized: an embryonic form associated with other congenital anomalies and a perinatal form in which bile ducts were presumably formed normally but underwent fibro-obliteration in the perinatal period. There are currently several proposed pathogenic pathways leading to the phenotype of BA, including an immune or autoimmune response to a perinatal insult (e.g. cholangiotropic viral infection) and dysregulated embryonic development of the extra- or intrahepatic biliary system. Recent advances in developmental biology, genomics and genetics, and cell immunology and biology, coupled with the development of appropriate animal models, have provided support for these postulated mechanisms. Future investigations combining animal model work and evaluation of clinical specimens holds the promise of identifying the etiology of BA and providing a scientific basis for treatment and preventative interventions.