Keywords
Forensic; Human pigmentation; Phenotype; SNaPshot; SNP
Abstract
LMC (Low Melanin Content) and HMC (High Melanin Content) subjects have respectively low and high melanin content in both skin and eyes; LMC has white skin and blue eyes and HMC has dark skin and eyes. Comparative investigation between frequencies of genetic variants in LMC subjects versus HMCsubjects may indicate which polymorphic variant is associated with melanin synthesis in skin and eyes. Coordinately, studies with Snow White-Like (SW) subjects may be informative to reveal any tissue-specific expression, since these individuals have white skin and dark eyes.
The LMC - HMC - SW model was used to analyze the allelic distribution of eight biallelic SNPs in pigmentrelated genes in admixed South Brazilian individuals. Based on allele frequencies of different human populations, allele “L” was used for the alleles associated with low melanin content populations (LMC subjects), and allele “H” was used for the alleles associated with high melanin content populations (HMC subjects). Allelic distribution of eight SNPs showed that 100% of LMC subjects (N=73) had less than eight H alleles, and 82% of HMC subjects (N=61) had eight or more H alleles. The AUC (Area under the Receiver Operating Characteristic Curve) value was 0.99, and the calculation of PGL (Pathway Genetic Load) and GP (Genetic Probability) showed that the SNP set presented 93% and 91% concordance between DNA genotype and phenotypes, respectively. Factorial Discriminant Analyses (FDA) performed in the SW group (light skin and dark eyes; N=116) showed a positive association between SNPs rs16891982 (SLC45A2), rs8045560 (MC1R), rs1426654 (SLC24A5), rs2733832 (TYRP1) and rs1042602 (TYR), and the LMC cluster for skin phenotype, and a positive association between SNPs rs4778138 (OCA2), rs12913832 (HERC2) and rs916977 (HERC2), and the HMC cluster for eye phenotype. The understanding of gene functionin externally visible characteristics is important for the prediction of skin and eye colors in humans; the analyses presented here are an important contribution to the forensic DNA phenotyping scenario.
Citation
Sawitzki FR, Rodenbusch R, Gubert DW, Prado MJ, Silva DSBS and Alho CS. Analysis of Eight SNPs in Pigment-Related Genes in South Brazilian Subjects with High or Low Skin and Eye Melanin Content. SM J Forensic Res Criminol. 2017; 1(2): 1008.