Clinical and Genetic Studies in Familial Non-medullary Thyroid Cancer

* INCLUSION CRITERIA: Subjects will be selected for this protocol based on either a clinical diagnosis of non-medullary thyroid cancer and the presence of one family member with the disease or the presence of 2 living family members with this disease. Patient selection for this protocol will not be based on gender, race, or ethnic background. In order to be eligible to participate in this study, an individual must meet all of the following criteria: * Adults or minor (\>= 7 years+), males and females. * An unaffected individual with (Bullet) 2 first-degree relatives who have or have had nonmedullary thyroid cancer OR -An affected individual with documented diagnosis of non-medullary thyroid cancer and (Bullet) one living relative with documented non-medullary thyroid cancer (Note: as this is a familial study, subjects do not need to present with the disease) OR * Any member of an affected family. (Note: for this study, an affected family is defined as a family having 2 or more 1st degree relatives with a documented diagnosis of FNMTC.) * Adults must be able to understand and the willingness to sign the informed consent document. * Adults must be able to complete the family history questionnaire. EXCLUSION CRITERIA: An individual who meets any of the following criteria will be not be allowed to enroll in this study: -Subjects unwilling/unable to give informed consent.