PUBLICATION
Identification of a wide spectrum of ciliary gene mutations in nonsyndromic biliary atresia patients implicates ciliary dysfunction as a novel disease mechanism
- Authors
- Lam, W.Y., Tang, C.S., So, M.T., Yue, H., Hsu, J.S., Chung, P.H., Nicholls, J.M., Yeung, F., Lee, C.D., Ngo, D.N., Nguyen, P.A.H., Mitchison, H.M., Jenkins, D., O'Callaghan, C., Garcia-Barceló, M.M., Lee, S.L., Sham, P.C., Lui, V.C., Tam, P.K.
- ID
- ZDB-PUB-210831-5
- Date
- 2021
- Source
- EBioMedicine 71: 103530 (Journal)
- Registered Authors
- Keywords
- Biliary atresia, Cilia dysfunction, Rare variants, Whole exome sequencing
- MeSH Terms
-
- CRISPR-Cas Systems
- Genetic Loci
- Humans
- Cell Line
- Mutation*
- PubMed
- 34455394 Full text @ EBioMedicine
Abstract
Background Biliary atresia (BA) is the most common obstructive cholangiopathy in neonates, often progressing to end-stage cirrhosis. BA pathogenesis is believed to be multifactorial, but the genetic contribution, especially for nonsyndromic BA (common form: > 85%) remains poorly defined.
Methods We conducted whole exome sequencing on 89 nonsyndromic BA trios to identify rare variants contributing to BA etiology. Functional evaluation using patients' liver biopsies, human cell and zebrafish models were performed. Clinical impact on respiratory system was assessed with clinical evaluation, nasal nitric oxide (nNO), high speed video analysis and transmission electron microscopy.
Findings We detected rare, deleterious de novo or biallelic variants in liver-expressed ciliary genes in 31.5% (28/89) of the BA patients. Burden test revealed 2.6-fold (odds ratio (OR) [95% confidence intervals (CI)]= 2.58 [1.15-6.07], adjusted p = 0.034) over-representation of rare, deleterious mutations in liver-expressed ciliary gene set in patients compared to controls. Functional analyses further demonstrated absence of cilia in the BA livers with KIF3B and TTC17 mutations, and knockdown of PCNT, KIF3B and TTC17 in human control fibroblasts and cholangiocytes resulted in reduced number of cilia. Additionally, CRISPR/Cas9-engineered zebrafish knockouts of KIF3B, PCNT and TTC17 displayed reduced biliary flow. Abnormally low level of nNO was detected in 80% (8/10) of BA patients carrying deleterious ciliary mutations, implicating the intrinsic ciliary defects.
Interpretation Our findings support strong genetic susceptibility for nonsyndromic BA. Ciliary gene mutations leading to cholangiocyte cilia malformation and dysfunction could be a key biological mechanism in BA pathogenesis.
Funding The study is supported by General Research Fund, HMRF Commissioned Paediatric Research at HKCH and Li Ka Shing Faculty of Medicine Enhanced New Staff Start-up Fund.
Genes / Markers
Figure Gallery (3 images)
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping