Related Experiment Video
Updated: Aug 12, 2026

Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
Published on: September 7, 2013
Multifactorial inheritance of white facial markings in the Arabian horse
1Department of Zoology, Arizona State University, Tempe 85287.
Abstract:
The hypothesis was tested that white facial markings in the Arabian horse show multifactorial inheritance. The hypothesis assumes that (1) alleles at different loci acting in a cumulative manner influence the variation in white facial markings, (2) the amount of whiteness is correlated with the number of genes, and (3) interacting nongenetic factors influence the variation. The study was based on computerized data obtained from the Arabian Horse Registry of America, Inc. The facial region was divided into five areas, and each horse was given a score according to the number of areas with a white marking. Twenty-two sire families were analyzed. Each sire family consisted of a sire, his foals, and the dams of those foals. The results of the investigation, including dam-foal and sire-foal regression analyses, were totally compatible with the hypothesis. A heritability study suggested that about two-thirds of the phenotypic variation in white facial markings among Arabian horses is attributable to genetic differences.
Related Concept Videos
Genetic Lingo
Pedigree Analysis
Epistasis
Incomplete Dominance
Background and Environment Affect 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...
Epistasis Analysis

