Forensic DNA Phenotyping for inference of characteristics of skin, eye and hair color in Brazilian sample

Abstract

DNA analysis for forensic investigations is based on the concept that each individual is unique genetically, except in cases of monozygotic twins. The DNA obtained from biological samples can individualize this material by direct comparison of the genetic profile, generated by analysis of STRs, obtained from biological sample of unknown origin with the profile of a reference sample. A major limitation of this technique is the need for a reference sample for comparison. Studies of single nucleotide polymorphisms (SNPs) that seek to understand the relationship between polymorphisms and certain phenotypic characteristics are growing and have generated promising results in helping to forensic science. The process of inferring externally visible characteristics (EVCs), among them the skin color, iris color and hair color, with forensic purpose, from the verification of their biological samples is known as Forensic DNA Phenotyping (FDP). Thus, FDP provides more detail on the subject to which certain biological sample belongs, without the need for a reference sample for comparative analysis. The use of this technology in admixed populations such as ours is recent and has been useful in determining the efficiency of these SNPs in the Brazilian population. Our previous project (Process FAPESP 2012/02043-6) evaluated 15 SNPs (11 of them are part of the Hirisplex system) and showed that some of these markers could be associated with the color characteristics of the skin, eyes and hair. From these results, we found interesting to extend the analysis to the rest of the markers used in Hirisplex and Hirisplex-S systems, already validated for phenotypic prediction of skin color, eye and hair in the scientific community and also assess the genetic ancestry of individuals using analysis of INDELS markers. (AU)