[1] With direct methods, genetic variants mechanistically linked with variable expression of the relevant phenotypes are measured and used with appropriate statistical methodologies to infer trait value.
[1] Biogeographic ancestry determination methods have been highly developed within the genetics community, as it is a key GWAS quality control step.
[3] As early as 2004, evidence was compiled showing that the bulk of phenotypic variation in human iris color could be attributed to polymorphisms in the OCA2 gene.
[5][6] More recently, companies such as Parabon NanoLabs and Identitas have begun offering forensic DNA phenotyping services for U.S. and international law enforcement.
Using the multiplex assay described in three separate papers, the genotype for 41 different SNPs can be generated, which are linked to hair, eye and skin color in humans.
[13][14] [6] The genotype can then be entered into the HIrisPlex-S Webtool[12] to generate the most probable phenotype of an individual based on their genetic information.no This tool originally started as the IrisPlex System, consisting of six SNPs linked to eye color (rs12913832, rs1800407, rs12896399, rs16891982, rs1393350 and rs12203592).
DNA phenotyping is used when investigators need to narrow the pool of possible individuals or identify unknown remains by learning about the person's ancestry and appearance.