Answer the questions "What's important for human health is the way we found the genes involved in dog coats and figured out howthey work together, rather than the genes themselves," said Elaine A. Ostrander, Ph.D., chief of the CancerGenetics Branch in NHGRI's Division of Intramural Research. "We think this approach will help pinpoint multiplegenes involved in complex human conditions, such as cancer, heart disease, diabetes and obesity."www.Biolnteractive.orghhmi BiolnteractiveMapping Genes to Traits in Dogs Using SNPsArtificial selection, at the heart of breeding for desirable traits in domesticated animals, hasyielded rapid change in a short span of canine history. While researchers estimate that modern dog breedsdiverged from wolves some 15,000 years ago, the genetic changes in the dog genome that create multiple coattypes are more likely to have been pursued by breeders in just the past 200 years. In fact, short-haired breeds,such as the beagle, display the original, more wolf-like versions of the three genes identified in the study.6. In two or three sentences, describe how scientists identified these genes.Modern dog breeds are part of a unique population structure, having been selectively bred for many years.Based on this structure, the researchers were able to break down a complex phenotype-coat into possiblegenetic variations. "When we put these genetic variants back together in different combinations, we found thatwe could create most of the coat varieties seen in what is among the most diverse species in the world thedog," Dr. Ostrander said. "If we can decipher the genetic basis for a complex trait such as the dog's coat, webelieve that we can do it as well with complex diseases."-Excerpt from a National Institutes of Health (NIH) News Release published August 27, 2009Answer the following questions to check your understanding of the reading.5. How many genes account for the wide variety of coat types in dogs?7. Why do you think it is important to analyze the DNA of many dogs when doing this research?8. Humans have SNPs too. In general, how might GWAS studies with dogs benefit humans?*PART 2: Applying GWAS to Dog Fur ColorLet's explore how a GWAS works using a simple example that compares two groups of dogs: dogs with black furand dogs with white fur. Table 1 shows the dogs' SNP alleles at 17 specific locations in the genome. Thesespecific locations in the genome are called loci (singular: locus). The SNP alleles at each locus are represented bytwo nucleotides, one from each parental chromosome.Table 1. SNP alleles at 17 different loci in dogs with black fur (first four rows) and dogs with white fur (last four rows).2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17A*Updated November 2020Page 3 of 7ActivityStudent Handout303CC AT CC GG AA TC TT CC GG AA TT GT AG AA CC GG ATSwww.Biolnteractive.orgCC AT AC GG GG TT TT CC GG AG TT GG AG AG CC GG ATCC AA AC CG GG TT TT CT GG AA TT GT AG AG CC TT ATShahCC AA AC GG AG TT TT CT GG GG TT GG AG AG CC GT ATUpdated November 2020Page 4 of 7hhmi BiolnteractiveMapping Genes to Traits in Dogs Using SNPsCC AT CC CG AATTAA CT GG AA TT GT AA AA CC GT ATActivityStudent HandoutCC AT CC GG AATTAA TC GG AA TT GG AG AA CC GG TTCC AT CC GG AATTAA CC GG AA TT GG AA AA CC GT ATCC AA CC GG AG TTAA TC GG GG TT GG AA AACC TT AT One way to find SNPs associated with a certain trait is by comparing groups with different versions of that trait.In a GWAS looking for genes that affect dog fur color, for example, we could compare the SNPs of twogroups: dogs with black fur and dogs with white fur. We would then determine which SNPs are significantlymore common in dogs with black fur compared to dogs with white fur. These SNPs are "markers" for regionsof the dog genome that contain genes affecting fur color.3. Why do you think SNPs are referred to as "markers" or "signposts"?Figure 3 shows several possibilities for why a SNP is associated with a certain trait. The SNP may be in the genethat causes the trait or in a regulatory area for that gene. If so, the SNP could directly affect the gene's functionand the resulting trait. However, some SNPs in or near a gene may have no effect on the gene or its trait.www.BioInteractive.orghhmi BioInteractiveMapping Genes to Traits in Dogs Using SNPsAssociated SNPsoutside of genea.no effect on proteinproduction or function.GAssociated SNPswithin geneno effect on proteinproduction or functionRegulatory sequencesACoding regionсTNoncoding SNP:changes amount ofprotein producedCausative SNPswithin geneUnassociated SNPfar from geneon same chromosomeor different chromosomeProteinCoding SNP:changes aminoacid sequenceb. Which types of SNPs might be identified in a GWAS?Updated November 2020Page 2 of 7ActivityStudent Handout4. Consider the different types of SNPs shown in Figure 3: associated, unassociated, and causative (includingboth noncoding and coding).Which types of SNPs affect protein production or function for the gene of interest?Figure 3. A diagramshowing various waysin which a SNP could beassociated with acertain gene and itstrait.GWAS in the NewsRead the following news release, which describes a GWAS study with dogs. Note that a dog's coat refers to itsfur or hair.Variants in Three Genes Account for Most Dog Coat DifferencesVariants in just three genes acting in different combinations account for the wide range of coat textures seen indogs from the poodle's tight curls to the beagle's stick-straight fur. A team led by researchers from theNational Human Genome Research Institute (NHGRI), part of the National Institutes of Health, reports thesefindings today in the advance online issue of the journai Science."This study is an elegant example of using genomic techniques to unravel the genetic basis of biologicaldiversity," said NHGRI Scientific Director Eric Green, M.D., Ph.D. "Genomics continues to gain new insights fromthe amazing morphological differences seen across the canine species, including many that give clues abouthuman biology and disease."Until now, relatively little was known about the genes influencing the length, growth pattern and texture of thecoats of dogs. The researchers performed a genome-wide scan of specific signposts of DNA variation, calledsingle nucleotide polymorphisms, in 1,000 individual dogs representing 80 breeds. These data were comparedwith descriptions of various coat types. Three distinct genetic variants emerged to explain, in combination,virtually all dog hair types."What's important for human health is the way we found the genes involved in dog coats and figured out how

Single nucleotide polymorphisms (SNPs) in GWAS are essential for understanding the genetic…

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11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...