A Retrospective Study of Clinical and Genetic Features in a Long-Term Cohort of Mexican Children with Alagille Syndrome

Alagille syndrome (ALGS) is a multisystem disorder characterized by a paucity of intrahepatic bile ducts and cholestasis, often requiring liver transplantation before adulthood. Due to the lack of genotype-phenotype correlation, case series are essential to understand disease presentation and prognosis. Data on Mexican ALGS patients are limited. Therefore, we aimed to characterize a large series of Mexican patients by consolidating cases from major institutions and independent geneticists, with the goal of generating one of the most comprehensive cohorts in Latin America. We retrospectively analyzed clinical records of pediatric ALGS patients, focusing on demographics, clinical features, laboratory and imaging results, biopsy findings, and transplant status. Genetic testing was performed for all cases without prior molecular confirmation. We identified 52 ALGS cases over 13 years; 22 had available clinical records. Of these, only 6 had molecular confirmation at study onset, prompting genetic testing in the remaining 16. We identified six novel <i>JAG1</i> variants and several previously unreported phenotypic features. A liver transplantation rate of 13% was observed in the cohort. This study represents the largest molecularly confirmed ALGS cohort in Mexico to date. Novel genetic and clinical findings expand the known spectrum of ALGS and emphasize the need for improved therapies, such as IBAT inhibitors, which may alleviate symptoms and reduce the need for transplantation.