Gaucher disease is an example of a “Mendelian” disorder, where defects in a single gene are the primary cause of the disease. Many common human diseases, such as hypertension, diabetes and arthrosclerosis, result from interactions between multiple genes and environmental factors such as diet, infections or exposure to toxins. In order to understand the changes in cellular mechanisms that result in these complex, or “multigenic’, diseases, researchers can gain information from rare, single gene disorders that share symptoms with more common, complex diseases.