Farber Disease Natural History Study

The primary objective of this study is to establish the natural history of Farber disease (acid ceramidase deficiency) through the collection and analysis of retrospective and prospective data on patients diagnosed with Farber disease. All patients diagnosed with Farber disease are eligible, including both those who have and have not undergone hematopoietic stem cell transplantation (HSCT). Additionally, data and records from deceased patients will provide valuable retrospective data for this study. The secondary objective of the study is to establish a set of clinical data, laboratory data (biomarkers), and functional data potentially useful for: * Assessing the efficacy of HSCT and the efficacy of potential future therapies (for example with RVT-801, recombinant human acid ceramidase) in Farber disease * Characterizing changes in symptoms of patients over time * Characterizing distinct groups (phenotypes) within the patient population * Documenting the disease histories of individual patients to serve as intra-subject control data for those who may enroll in any future clinical studies with therapies for Farber disease The exploratory objectives of the study are: * To explore the relationship between patient disease activity or phenotype and specific ceramide levels or specific immunologic markers (cytokines/chemokines) in blood * To evaluate a standardized tool, the Farber Disease Natural History Instrument (FDNI), to be used for the collection of patient history information, data from clinical, laboratory, genetic, and functional studies, and data from review of medical records