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Understanding Familial DNA Searching: Coming to a Consensus on Terminology

NCJ Number
Emily Niedzwiecki; Sara Debus-Sherrill; Michael B. Field
Date Published
June 2017
Since different definitions and interpretations of familial DNA searching (FDS) have been used in the literature, this white paper discusses terminology issues, identifies key characteristics that distinguish FDS from other practices, outlines the FDS process, and provides a unified definition to assist in alleviating confusion in the field.
Following the introduction, this paper's second section, "A Review of Familial DNA Searching," reviews the key characteristics that distinguish FDS from partial matching (PM), and it also provides an overview of definitions offered by various sources. The paper's third section, "Definitions," presents FDS and PM definitions compiled from multiple sources and from the consensus of a roundtable of experts. FDS is defined as "A deliberate search of a DNA database using specialized software (separate from CODIS) to detect and statistically rank a list of potential candidates in the DNA database who may be close biological relatives (e.g., parent, child, sibling) to the unknown individual contributing the evidence DNA profile, combined with lineage testing (e.g., Y-STR, mtDNA) to confirm or refute biological relatedness." The definition of "partial matching" is "A moderate stringency search of a DNA database using the routine search parameters within CODIS that results in one or more partial matches between single-source and non-degraded DNA profiles that share at least one allele at each locus, indicating a potential familial relationship between the known individual in the DNA database and the unknown individual contributing the evidence DNA profile. Disclosing or proceeding with a partial match would be to use information learned through partial matching in an investigation." The paper's fourth section, "Familial Searching and Partial Matching in Practice," describes the core components of FDS and PM, with attention to how these practices differ. 1 figure and 33 references