Forensic DNA Phenotyping

Forensic DNA Phenotyping (FDP) is a technique that predicts externally visible characteristics (EVCs) like skin color, eye color, hair color, height, facial features, and male baldness pattern from biological samples, without needing a reference sample. It uses short tandem repeats (STRs) and single nucleotide polymorphism (SNP) multiplexing. Systems like IrisPlex and Snipper 2.5 have been developed for this purpose. Eye color can be predicted with over 90% accuracy using Irisplex, while hair color prediction models have an accuracy of 75-92%. Skin color prediction models have an accuracy of 72-97%, and height prediction models have an accuracy of around 75%. The genetic basis of male pattern baldness accounts for about 80% of its heritability, with a prediction accuracy of 76.2% that rises to 86.4% with the inclusion of 10 markers. Age estimation can be achieved with high accuracy using DNA methylation detection methods. Ancestry can be inferred using ancestry informative markers (AIMs). The document concludes that these techniques are already being used in forensic investigations with high accuracy, but more diverse population studies are needed to confirm the data.