One mission of the ACMG Laboratory Quality Assurance (QA) Committee is to develop standards and guidelines for clinical genetics laboratories, including cytogenetics, biochemical, and molecular genetics specialties. This document was developed under the auspices of the Molecular Subcommittee of the Laboratory QA Committee by the Huntington Disease (HD) Working Group. These guidelines are not to be interpreted as restrictive or the only approach but to provide a helpful guide. Certainly, appropriately trained and credentialed laboratory directors have flexibility to utilize various testing platforms and design testing strategies with considerable latitude. We felt that it was essential to include technique-specific guidelines of several current technologies commonly used in laboratories providing HD testing, because the technologies discussed are available commercially and are widely utilized. We take the view that these technologies may change, and thus this document may change with future review.