Biliary atresia is associated with polygenic susceptibility in ciliogenesis and planar polarity effector genes

• DOI: 10.1016/j.jhep.2023.07.039
• Publication Date: 2023-08-11T01:29:53Z
• Authors: Joseph T. Glessner; Mylarappa B. Ning...; Kim A. Ngo; Maliha Zahid; Juhoon So; Brandon W. Higgs; Patrick M.A. Sleiman; Tejaswini Narayanan; Sarangarajan Rang...; Michael March; Krishna Prasadan; Courtney Vaccaro; Miguel Reyes-Mugica; Jeremy Velazquez; Claudia M. Salgado; Mo R. Ebrahimkhani; Lori Schmitt; Dhivyaa Rajasundaram; Morgan Paul; Renata Pellegrino; George K. Gittes; Dong Li; Xiang Wang; Jonathan Billings; Robert Squires; Chethan Ashokkumar; Khalid Sharif; Deirdre Kelly; Anil Dhawan; Simon Horslen; Cecilia W. Lo; Donghun Shin; Shankar Subramaniam; Hakon Hakonarson; Rakesh Sindhi
• Keywords: Canada; Clinical Sciences; Chronic Liver Disease and Cirrhosis; 610; Clinical sciences; Oral and gastrointestinal; Article; Mice; Rare Diseases; Biliary Atresia; Infant Mortality; Genetics; 2.1 Biological and endogenous factors; Animals; Humans; Genetic Predisposition to Disease; Aetiology; Child; Zebrafish; Pediatric; Transplantation; Biomedical and Clinical Sciences; Ciliogenesis; Tube Morphogenesis; Gastroenterology & Hepatology; Portal Vein; Liver Disease; Prevention; Human Genome; Organ Transplantation; Perinatal Period - Conditions Originating in Perinatal Period; 3. Good health; Public Health and Health Services; Congenital Structural Anomalies; Polygenic Susceptibility; Digestive Diseases; Vascular Development; Genome-Wide Association Study

Biliary atresia (BA) is poorly understood and leads to liver transplantation (LT), with the requirement for and associated risks of lifelong immunosuppression, in most children. We performed a genome-wide association study (GWAS) to determine the genetic basis of BA.We performed a GWAS in 811 European BA cases treated with LT in US, Canadian and UK centers, and 4,654 genetically matched controls. Whole-genome sequencing of 100 cases evaluated synthetic association with rare variants. Functional studies included whole liver transcriptome analysis of 64 BA cases and perturbations in experimental models.A GWAS of common single nucleotide polymorphisms (SNPs), i.e. allele frequencies >1%, identified intronic SNPs rs6446628 in AFAP1 with genome-wide significance (p = 3.93E-8) and rs34599046 in TUSC3 at sub-threshold genome-wide significance (p = 1.34E-7), both supported by credible peaks of neighboring SNPs. Like other previously reported BA-associated genes, AFAP1 and TUSC3 are ciliogenesis and planar polarity effectors (CPLANE). In gene-set-based GWAS, BA was associated with 6,005 SNPs in 102 CPLANE genes (p = 5.84E-15). Compared with non-CPLANE genes, more CPLANE genes harbored rare variants (allele frequency <1%) that were assigned Human Phenotype Ontology terms related to hepatobiliary anomalies by predictive algorithms, 87% vs. 40%, p <0.0001. Rare variants were present in multiple genes distinct from those with BA-associated common variants in most BA cases. AFAP1 and TUSC3 knockdown blocked ciliogenesis in mouse tracheal cells. Inhibition of ciliogenesis caused biliary dysgenesis in zebrafish. AFAP1 and TUSC3 were expressed in fetal liver organoids, as well as fetal and BA livers, but not in normal or disease-control livers. Integrative analysis of BA-associated variants and liver transcripts revealed abnormal vasculogenesis and epithelial tube formation, explaining portal vein anomalies that co-exist with BA.BA is associated with polygenic susceptibility in CPLANE genes. Rare variants contribute to polygenic risk in vulnerable pathways via unique genes.Liver transplantation is needed to cure most children born with biliary atresia, a poorly understood rare disease. Transplant immunosuppression increases the likelihood of life-threatening infections and cancers. To improve care by preventing this disease and its progression to transplantation, we examined its genetic basis. We find that this disease is associated with both common and rare mutations in highly specialized genes which maintain normal communication and movement of cells, and their organization into bile ducts and blood vessels during early development of the human embryo. Because defects in these genes also cause other birth defects, our findings could lead to preventive strategies to lower the incidence of biliary atresia and potentially other birth defects.