Exam 21: Genetic Analysis of Quantitative Traits

Of mean, median, and modal, what value is the most common value in a given population?

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 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?

QTLs are most often mapped relative to DNA markers by using what scores as measurement?

A GWA study relies on the correlation between a QTL and a ________.

What is meant by a QTL?

It is clearly established that obesity has greatly increased in children over the last several decades in the United States. While several genes have been identified that increase the potential for obesity, environmental influences are also involved. Which of the following is most likely?

A group is experimenting with selection in an insect species due to exposure to a newly developed insecticide, cpd AW143. The group has found that after 10 generations of exposure, the population is now bimodal in its response to the drug. Close to 30% of the population are completely normal while 70% live only about 1/6 of the normal lifetime. This is an example of __________.

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

A polygenic trait is influenced by the effect of several genes. Although one or more of these may be major genes, many others with lesser effects are known as what type of gene?

After locating a genome region likely to include a QTL, what must be found in this region?

If a trait results from genetic variation as well as environmental factors, it is known as a ________ trait.

Although no specific gene alteration has yet been demonstrated as a cause for schizophrenia (SZ), it is known to have a strong genetic component. A recent study has found a strong association between SZ and a locus at chromosome 10q22-23 in Ashkenazi Jewish and Taiwanese Han populations. Which of the following is probable?

It is estimated that 4.6% of SNPs and about 17% of all genes can be defined as pleiotropic. Based on this finding, which of the following should a consumer of genetic information keep in mind?

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?

If we suppose that a specific QTL is genetically linked to a DNA marker at a recombination frequency of 10%, then the parental type combinations in gametes would be expected at what frequency?

If H2 for club foot is estimated as 80%, would you expect a small difference in concordances between MZ and DZ twins, such as 30 versus 27, or a large difference, such as 30 versus 2?

Distinguish between broad sense heritability and narrow sense heritability, and explain how either or both of these measures can be used to inform those using artificial selection.

Until recently, only apolipoprotein E (APOE)polymorphisms have been found to correlate with late-onset (nonfamilial)Alzheimer disease (AD); however, these account for less than 50% of the V_G. New GWA studies have found a chromosome 12 risk locus. What method will likely be used by AD researchers going forward?

A homozygous plant has sepals of 30-cm flowers while another homozygote of the same species has 40-cm flowers. The F1 flowers are all 35 cm. In the F₂, out of 600 plants the smallest flowers were 30 cm and the largest were 40cm; all the others were of intermediate sizes. If all the genes involved in flower size are additive, how many gene pairs are there?

QTL mapping resembles linkage analysis primarily because __________.