Skin color estimation for phenotypic character identification in the Turkish population

Phenotypic traits can be predicted from biological evidence found at crime scenes via DNA analysis. This method makes it easier to identify suspects and victims and relate them to the crime scene by using molecular genetics. Through predicting externally visible characteristics (EVCs) like eye, hair, and skin color from biological material, forensic DNA phenotyping (FDP) helps criminal investigations by recognizing unknown people and decreasing the number of possible suspects. FDP predicts phenotypic characteristics including skin, hair, and eye color by using pigmentation. It is crucial to test the population and verify the success of the estimation technique prior to use FDP in case studies. The IrisPlex system, created by Walsh et al., is used to estimate eye color, and the HIrisPlex system is used to estimate both eye and hair color. The HIrisPlex-S system, created by Chaitanya et al., provides for the simultaneous prediction of skin, eye, and hair color. SNPs, or single nucleotide polymorphisms, are used in this predicting system. The HIrisPlex-S prediction system has 41 SNP areas in total, 17 of which are related to skin color. Phenotype probabilities are established for five skin colors. In this study, the skin color prediction success of 100 individuals from the Turkish population was evaluated with the HIrisPlex-S system. The HIrisPlex-S online web tool was used for skin color prediction. The HIrisPlex-S system's sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated. According to the study's results, the prediction success rate was 82.4% for dark, 60% for pale, 100% for intermediate, and 20% for very pale skin. All of the people with intermediate skin tones had their skin color accurately predicted. Since there was no dark to black skin color among the volunteers, prediction could not be made for this phenotype. Our study shows that the HIrisPlex-S system can be applied in forensic case studies in Türkiye.