| DNA profiling methods have undergone vast improvements in the past two decades, yet all still require a reference sample for comparison. To overcome this, research into using DNA analyses to create a physical profile for unknown suspects or victims that can aid in their identification has begun. The purpose of this thesis project was to develop a preliminary genetic assay for estimating an individual's scalp hair color from a biological sample. Multiplex PCR and SNP primer extension assays were developed, and eight SNPs in three genes (rs1426654 in SLC24A5; rs16891982 and rs26722 in SLC45A2; rs7495174, rs4778138, rs4778241, rs1800404, and rs1448484 in OCA2) were genotyped for 85 DNA samples from African American individuals. A statistical model for estimating scalp hair pigmentation from the SNP genotypes while controlling for ancestry was generated. ANCOVA analyses revealed that OCA2 SNPs rs1800404, rs7495174, rs4778138, and rs4778241, and SLC4SA2 SNPs rs1448484 and rs16891982 had the most significant effects on hair pigmentation. SNP rs7495174 had the only significant effect individually (p ≤ 0.022), while the others correlated via SNP--SNP interactions (p-values ranging from 0.005 to 0.049). The final corrected model explained 66.7% percent of the variation in hair pigmentation (p = 0.017; 1 - beta = 0.932) in the individuals studied, providing groundwork for quantitatively predicting hair pigmentation in an unknown individual. |
