The genetic etiology of many disorders of interest to the orthopaedist now is known. Based on this information, these disorders can be grouped broadly based on the function of the causative gene into five categories: structural, tumor and cell regulatory, developmental, important in nerve or muscle function, and protein processing (enzymes). In addition, some disorders are caused by large chromosomal abnormalities, which comprise a sixth class. Disorders in each of these categories share similarities in their clinical manifestations, treatment, prognosis, and inheritance pattern. This classification is a useful way to remember the major clinical manifestations and treatment principles for genetic disorders of interest to the orthopaedist.