Related Experiment Video
Updated: Jun 16, 2026
07:16
Reverse Genetic Approach to Identify Regulators of Pigmentation using Zebrafish
Published on: March 1, 2022
Predicting phenotype from genotype: normal pigmentation
Robert K Valenzuela1, Miquia S Henderson, Monica H Walsh
1Department of Pediatrics, College of Medicine, University of Arizona, Tucson, AZ 85724, USA.
Journal of Forensic Sciences
|February 18, 2010
Summary
Forensic DNA analysis can predict hair, skin, and eye color using specific genetic markers. This study identified key single nucleotide polymorphisms (SNPs) for predicting pigmentation from forensic samples.
Area of Science:
- Forensic genetics
- Human genetics
- Population genetics
Background:
- Forensic DNA analysis primarily relies on matching samples within databases like CODIS.
- Unmatched DNA samples in forensic investigations offer limited investigative leads.
- Predicting donor characteristics from DNA is crucial for unidentified samples.
Purpose of the Study:
- To identify genetic markers associated with human pigmentation traits.
- To develop predictive models for hair, skin, and eye color from forensic DNA.
- To assess the utility of these markers across diverse ethnic backgrounds.
Main Methods:
- Genotyping of 75 single nucleotide polymorphisms (SNPs) in 24 candidate genes.
- Analysis of associations between SNPs and pigmentation phenotypes (hair, skin, eye color).
- Utilizing multiple linear regression modeling on data from 789 individuals.
Main Results:
- Five SNPs in five distinct genes significantly explained a large portion of pigmentation variation.
- These predictive models demonstrated effectiveness across various ethnic groups.
- The identified SNPs are strongly correlated with hair, skin, and eye color.
Conclusions:
- Specific SNPs can accurately predict an individual's pigmentation from forensic DNA samples.
- These findings enhance the investigative potential of unidentified DNA evidence.
- The predictive models are independent of the donor's ethnic origin, broadening forensic applicability.
Related Concept Videos
01:39Epistasis
In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence phenotypes in a phenomenon called epistasis. For example, rabbit fur can be black or brown depending on whether the animal is homozygous dominant or heterozygous at a TYRP1 locus. However, if the rabbit is also homozygous recessive at a locus on the tyrosinase gene (TYR), it will have an unshaded coat that appears white, regardless of its TYRP1...
01:19Pigmentation
The color of the skin is influenced by a number of pigments, including melanin, carotene, and hemoglobin. Recall that melanin is produced by cells called melanocytes, which are found scattered throughout the stratum basale of the epidermis. The melanin is transferred to the keratinocytes via melanosomes.
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
02:27Background and Environment Affect Phenotype
Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
01:09Epistasis Analysis
Although Mendel chose seven unrelated traits in peas to study gene segregation, most traits involve multiple gene interactions that create a spectrum of phenotypes. When the interaction of various genes or alleles at different locations influences a phenotype, this is called epistasis. Epistasis often involves one gene masking or interfering with the expression of another (antagonistic epistasis). Epistasis often occurs when different genes are part of the same biochemical pathway. The...
01:33Pleiotropy
Pleiotropy is the phenomenon in which a single gene impacts multiple, seemingly unrelated phenotypic traits. For example, defects in the SOX10 gene cause Waardenburg Syndrome Type 4, or WS4, which can cause defects in pigmentation, hearing impairments, and an absence of intestinal contractions necessary for elimination. This diversity of phenotypes results from the expression pattern of SOX10 in early embryonic and fetal development. SOX10 is found in neural crest cells that form melanocytes,...
01:11Genetic Lingo
Overview