Forensic DNA Phenotyping and the Prediction of Externally Visible Physical Characteristics

Forensic DNA Phenotyping (FDP) tests compile genetic markers closely associated with common variation in externally visible physical characteristics including pigmentation traits, freckling, hair shape, and hair loss in men. As such, FDP tests provide key information about the likely appearance of a suspect when investigators lack eyewitness testimony or have not obtained a database match to the DNA recovered from the crime scene. The sophistication and informativeness of FDP tests have grown markedly in recent years, resulting from growing knowledge of genome-wide patterns of variation and the association studies of common characteristics which highlight the most closely associated markers in each trait. The number of markers that can be analyzed from contact trace DNA has been considerably enhanced with the recent adoption of massively parallel sequencing technology, paving the way for much more extensive FDP tests that can encompass a wider range of physical characteristics and a larger number of associated markers in a single forensic analysis.