This publication extends the now classic system of human cytogenetic nomenclature prepared by an expert committee and published in collaboration with 'Cytogenetic and Genome Research' since 1963. Revised and finalized by the ISCN Committee and its advisors at a meeting in Seattle, Wash., in April 2012, the "ISCN 2013" updates, revises and incorporates all previous human cytogenetic nomenclature recommendations into one systematically organized publication that supersedes all previous ISCN recommendations.