Exam 21: Genetic Analysis of Quantitative Traits

It is estimated that 4.6% of SNPs and about 17% of all genes can be defined as pleiotropic.Which of the following might be a significant lesson for a consumer of genetic information based on this finding?

Parkinson disease (PD)is a neurodegenerative disease that has been associated with a significant number of different genes,therefore showing it to be genetically heterogenic.One recent study in 278 families found evidence of two such possible loci.Evidence for linkage to chromosome 18q11 was presented by Gao et al.in 2009.Which of the following would be considered reputable evidence for this?

QTL mapping resembles linkage analysis primarily because

Mean platelet volume (MPV)in humans increases with heart attacks and strokes and is used to predict recurrence as well as mortality.MPV has high heritability.A recent GWA study found MPV to be associated with three SNPs on chromosomes 12,3,and 17 respectively.These three QTLs accounted for 4-5% of MPV variance.Which of the following is a reasonable explanation?

Which component of variance in a trait such as stamina in horses is the best indicator of whether the trait will respond to selection?

An animal breeder asks your advice about which of a number of traits could most effectively be selected for in his herd.Which would you most correctly suggest?

For a specific desirable trait in a breed of sheep,VP is 28.6,VC is 11,and VA is 7.2.What is its broad sense heritability?

A recent study investigated the heritability of lean body mass (LBM)that had been previously reported as between 52 and 84% but without known specific genes.The authors used a genome-wide association (GWA)scan to identify two SNPs: rs16892496 and rs7832552 within the thyrotropin-releasing hormone receptor gene that were significantly associated with LBM.Since the gene in question involves muscle metabolism,which of the following would you predict would be associated with LBM in a given population?

Calculate the narrow sense heritability (h₂)for the following data on a trait in turkeys: VA = 11.0 VE = 94.4 VP = 114.2 VD = 13.8

If a trait results from the action of several genes,it is called a ________ trait.

Describe how quantitative traits can be explained in Mendelian terms.

Given a list of the percentage of monozygotic and dizygotic twins in concordance for a selection of traits,describe how you would evaluate the relative input of environmental versus genetic factors.

A strain of a cereal grain can be either dark tan,medium-dark tan,medium tan,light tan,or cream colored.When a dark tan and a cream plant are crossed,all F₁ are medium tan.The F₂ are distributed in a ratio of 1:4:6:4:1 from darkest to lightest.How many additive alleles are needed to produce the darkest phenotypes?

Many human behavioral traits have both genetic and environmental components.Bipolar disorder has long been known to be familial,and more recently a number of genes and/or SNPs have been found to be involved.What are three or more reasons that this research has been hampered?

Which of the following best predicts the response of a trait to artificial selection?

Of the variance and the standard deviation for a set of data about a trait,which represents the square of the difference between each of the values and the mean of the sample,divided by the degrees of freedom?

Recent work in Drosophila demonstrated that the genes known as the chromatin remodeling complex co-localize at loci for hsp genes that respond to heat shock.Outline a procedure you could use to substantiate this finding.

Which will exhibit the most shared maternal effects (uterine environment,etc.): identical or fraternal twins?

What is meant by a QTL?

If lean body mass (LBM)and SNPs in the gene for a G-coupled receptor for a hormone secreted by the hypothalamus are associated,and the binding of this hormone is the first step in the release of thyroxin (necessary for skeletal muscle development),then increases in mutations in the hormone receptor gene would be expected to