Browsing by Author "Roininen, Nelli Aurora"

Externally visual characteristics such as hair, skin and eye pigmentation or clothes have always been used for suspect identification. Also the opposite - to link unknown body parts or only DNA to a person - is recently tried to be introduced into forensics. I am testing the feasibility of one such method, IrisPlex, in Finnish population. The IrisPlex method was first published by Walsh et al. (2011). IrisPlex uses six single nucleotide polymorphisms (SNPs) in different genes found to affect the most in eye color variation. SNPs were detected from DNA sample by single base extension method, SNaPshot. Based on this information from DNA of a participant, the prediction of the most probable eye color was generated with a multinomial regression model. Also the genotypic information in the six loci and differences between Eastern and Western Finns were studied. In addition, this study supplements the knowledge of eye color frequencies across Europe. This study revealed that IrisPlex does work appropriately in Finns when detecting the blue and brown eye colors: 80% of the study participants' eye colors were predicted correctly. The biggest weakness of IrisPlex is its incapability to predict the intermediately colored eyes. Prediction probability differences between genders were not detected. In the study population 60% of the participants had blue eyes (28 individuals), 13% had brown eyes (6 individuals) and 28% (13 individuals) intermediately colored eyes. When the eyes were divided into two categories, the portion of blue-eyed participants was 77% (36 individuals) and brown-eyed participants 23% (11 individuals). These results are consistent with previous studies and update the color frequencies. Genetic segmentation of Finnish people in Eastern and Western Finland has been established in multiple studies. In addition to previous ones, this study is consistent with the genetic segmentation theory between Eastern and Western Finland. Darker eyes were observed slightly more frequently in participants with north-east heritage than in participants with south-west heritage. However, the studied populations were small and the result was insignificant. Additionally, the studied population sample represents the narrow gene pool of the Finns; almost half of the participants, 42%, reported all or 3 of their grandparents to have been born in the same village. The allele and genotype frequencies were also studied and compared to another study, in which these SNPs have been studied in the Finns and the results were consistent. Altogether, this study strengthens the evidence that IrisPlex has potential in forensic, archeological and anthropological applications even in genetically isolated populations as the Finns. This study supports the IrisPlex method to be further developed and especially addresses the need for better sensitivity for intermediate eye color.