The Utility of Hierarchical Genetic Testing in Pediatric Liver Disease

Background: Genetic factors underlie a substantial proportion of pediatric liver diseases. Hereditary liver diseases have considerable genetic heterogeneity and variable clinical manifestations, which bring great challenges to clinical and molecular diagnoses. Method: In this study, we investigated a group of pediatric patients with varying degrees of liver dysfunction using a hierarchical strategy. We first applied a sequencing panel encompassing 166 known causal genes of liver disease. We then used exome sequencing (ES) in those patients whose cases remained undiagnosed to identify the genetic etiology of their symptoms. Findings: In total, we enrolled 131 unrelated pediatric patients with liver disease of Chinese Han ethnicity. We first applied targeted gene sequencing of 166 genes to all patients and yielded a diagnostic rate of 35.9% (47 of 131). Eighty-four patients who remained undiagnosed after target gene sequencing were subjected to ES. As a result, eight (8/84, 9.5%) of them obtained molecular diagnoses, including four patients suspected of abnormal bilirubin metabolism and four idiopathic cases. Non-typical genetic findings, including digenic inheritance and dual molecular diagnosis, were also identified. Through a comprehensive assessment of novel candidate variants of uncertain disease association, eleven patients of the remaining undiagnosed patients were able to obtain likely molecular diagnoses. Interpretation: Our study presents evidence for the diagnostic utility of sequential genetic testing in a cohort of patients with pediatric liver disease. Our findings expand the understanding of the phenotypic and mutational spectrum underlying this heterogeneous group of diseases. Funding Information: This research was funded in part by the Natural Science Foundation of Beijing Municipality (JQ20032 to N.W., 7191007 to Z.W.), National Natural Science Foundation of China (81822030 and 82072391 to N.W., 81930068 and 81772299 to Z.W., 81972037 to T.J.Z.), Tsinghua University-Peking Union Medical College Hospital Initiative Scientific Research Program, CAMS Innovation Fund for Medical Sciences (CIFMS 2020-I2M-C&T-B-030 to T.J.Z.), Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences (No. 2019PT320025), and Capital characteristic project (Z181100001718030 to M.Z.). Declaration of Interests: The authors declare no conflicts of interest. Ethics Approval Statement: This study was approved by the Research Ethics Committee of the Fifth Medical Center of Chinese PLA General Hospital (IRB ID: 2020078D). Consent forms were obtained from all patients or guardians.