Cholestatic Liver Disease

The goal of this clinical trial is to learn whether adding calcitriol to vitamin D2 can improve vitamin D deficiency in children with cholestasis and chronic liver disease. Cholestasis is a condition in which bile flow is reduced, which can make it difficult for the body to absorb and process vitamin D. The study will also learn about the safety of using vitamin D2 together with calcitriol. The main questions it aims to answer are: * Does vitamin D2 plus calcitriol increase blood 25-hydroxyvitamin D (25-OHD) levels more than vitamin D2 alone after 3 months of treatment? * Does vitamin D2 plus calcitriol help more children reach an adequate vitamin D level by 3 and 6 months? * What medical problems, especially high calcium or high phosphorus levels, occur during treatment? Researchers will compare children who receive vitamin D2 alone with children who receive vitamin D2 plus calcitriol to see which treatment improves vitamin D levels more effectively and safely. Participants will: * Take vitamin D2 alone or vitamin D2 plus calcitriol as assigned by randomization * Visit the clinic for study assessments at the start of the study, at 3 months, and at 6 months * Have blood tests to measure vitamin D levels, calcium, phosphorus, parathyroid hormone, liver function, and other safety markers * Have their treatment reviewed at 3 months; participants whose vitamin D level remains low may have their treatment adjusted according to the study plan * Bring back medication packages so researchers can check how regularly the study medicines were taken

Cholestatic disease in adults comprises a heterogeneous group of conditions characterized by intra- or extrahepatic alterations of bile flow that can lead to fibrosis or hepatic decompensation. Due to the heterogeneity of clinical manifestation, which is sometimes very subtle, diagnosis based on clinical, histological, and radiological evaluation is often very complicated. Genetic testing can be helpful in identifying the cause of the clinical phenotype, thereby allowing for targeted follow-up adequate to the patient's specific characteristics and risk factors. Although the utility of genetic analysis has been well documented for other liver diseases or in pediatric cohorts of children with cholestatic disease, the use and benefits of genetic testing in adults with cholestatic disease are still little explored and investigated. In this context, through the use of whole-genome sequencing (WGS), the FIRST project aims to evaluate the role of rare genetic variants in the pathogenesis of cholestatic disease and the utility of WGS in defining a genetic diagnosis.

A Phase 1, Open-label Extension Groups Study in Subjects having Hepatic Impairment with Cirrhosis due to Cholestatic Liver Disease

Evaluating Pharmacokinetic and safety of Saroglitazar Magnesium 1 mg when dosed on alternate days in subjects having moderate hepatic impairment with cirrhosis due to cholestatic liver disease

Genotype-phenotype relationship between adult cryptogenic cholestasis and mutations in genes responsible for progressive familial intrahepatic cholestasis

This is a cross-sectional, multicenter tissue study with an exploratory aim to estimate the prevalence of genetic mutations that predispose individuals to diseases in the context of cholestatic disorders and hepatobiliary neoplasms. It is intended as a hypothesis-generating study for future empirical investigations.