Gene Polymorphism and Human Pigmentation

• NCJ Number: 223980
• Author(s): Murray H. Brilliant Ph.D.
• Date Published: September 2008
• Length: 60 pages
• Grant Number(s): 2002-IJ-CX-K010
• Agencies: NIJ-Sponsored
• Publication Type: Report (Study/Research)
• Award: Gene Polymorphism and Human Pigmentation

Annotation

The goal of the study was to determine with a high degree of accuracy the pigmentation phenotype (hair, eye, and skin color) of an individual from a forensic DNA sample.

Abstract

Using multiple linear regression (MLR) modeling, six Single Nucleotide Polymorphisms (SNPs) in five genes were found to account for large proportions of pigmentation variation in hair, skin, and eyes in the across-population analyses; single polymorphisms in SLC45A2, SLC24A5, and OCA2 accounted for 77.3 percent of the variance in total amount of scalp-hair melanin; single polymorphisms in SLC45A2, SLC24A5, and MC1R accounted for 38.3 percent of the variance in the natural logarithm of the ratio of black-to-red melanin in scalp hair; single polymorphisms in SLC45A2, SLC24A5, and ASIP accounted for 45.7 percent of the variance in skin pigmentation; and single polymorphisms in SLC45A2, SLC24A5, and OCA2 accounted for 52.2 percent of the variance in eye color. Interaction between ASIP and SLC45A2 were inferred from the models and increased the explanation of skin pigmentation variation to 49.6 percent. Thus, these models offer useful predictive tools by using only three SNPs to determine an individual’s pigmentation type, independent of ethnic origin. The analyses proceeded in three phases. Phase one was the determination of the spectrum of polymorphism in these genes in a limited number of individuals of diverse ethnic origins and various pigmentation types. Phase two was the correlation of these SNPs with pigmentation types in a representative sample of individuals. Phase three was the testing of the models determined in Phase two and the adaptation of the analysis to forensic DNA samples. Phases one and two have been completed, and Phase three is nearly complete. 9 figures and 93 references