Question 1

Which of the following is a type of association analysis that is designed to avoid issues with population stratification?&#10;A) Case-control study&#10;B) Transmission disequilibrium test&#10;C) Autozygosity mapping&#10;D) Affected sib pair method&#10;E) NPL analysis

Accepted Answer

The transmission disequilibrium test (TDT) is a type of association analysis that is designed to avoid issues with population stratification. It uses data on parents and affected offspring to determine if a particular allele is transmitted significantly more or less than expected from Mendelian inheritance. This eliminates the potential impact of population stratification, as the parents of the affected offspring serve as their own controls. Choice A, C, D, and E are not specifically designed to address issues with population stratification.

Question 2

The strategy behind association analyses is to look in affected populations for allele sharing in which of the following?&#10;A) The disease gene&#10;B) The disease chromosome&#10;C) The founder haplotype&#10;D) Regions of homozygosity&#10;E) Regions of similarity

Accepted Answer

The strategy behind association analyses, particularly in the context of genetic studies, involves looking for allele sharing in the founder haplotype among affected populations. This approach helps identify genetic variations that are more common in individuals with a specific disease compared to those without the disease, aiding in understanding the genetic basis of diseases.

Question 3

To search for loci involved in autosomal recessive diseases,which alternative approach to a traditional linkage analysis can be used?&#10;A) Look for shared alleles between affected families&#10;B) Look for shared regions of deletion between affected families&#10;C) Look for regions of homozygosity in affected families&#10;D) Look for uniparental heterodisomy&#10;E) Look for uniparental homodisomy

Accepted Answer

Looking for regions of homozygosity in affected families is an alternative approach to traditional linkage analysis. In autosomal recessive diseases, affected individuals inherit two copies of a mutated gene, one from each parent. If the parents are carriers (heterozygous), then they will only have one mutated copy, and the disease will not manifest in them. Thus, affected individuals are likely to have regions of the genome where they are homozygous for the mutated allele. By comparing the genome of affected individuals in a family, one can identify regions of homozygosity that are likely to contain the gene responsible for the disease.

Question 4

What is the explanation for the relatively high frequency of rare autosomal recessive disorders in the Old Order Amish population?&#10;A) Assortative mating&#10;B) Positive selection&#10;C) Negative selection&#10;D) Founder effect&#10;E) Heterozygote advantage

Accepted Answer

The relatively high frequency of rare autosomal recessive disorders in the Old Order Amish population is attributed to the Founder effect. Due to the small founding population size and subsequent genetic isolation, rare alleles become more frequent in the population through genetic drift. This can lead to a higher frequency of diseases caused by recessive alleles if the rare allele happens to be disease-causing.

Question 5

Which of the following describes the relative genotype frequencies in a randomly mating population?&#10;A) Law of random segregation&#10;B) Law of natural selection&#10;C) Hardy-Weinberg principle&#10;D) Law of independent assortment&#10;E) Darwin's principle

Accepted Answer

The Hardy-Weinberg principle describes the relative genotype frequencies in a randomly mating population, assuming that the population is large, mating is random, mutation, gene flow, and natural selection are absent, and there is no genetic drift. The principle states that the frequencies of alleles and genotypes in a population will remain constant from generation to generation, and can be used to calculate expected genotype frequencies based on observed allele frequencies.

Question 6

The incidence of cystic fibrosis in the Caucasian population is approximately 1 in 4000-what is the carrier frequency?&#10;A) 1/16&#10;B) 1/32&#10;C) 1/64&#10;D) 1/128&#10;E) 1/1000

Accepted Answer

The carrier frequency is the proportion of the population that carries one copy of the CF gene. To calculate this, we use the formula:
Carrier frequency = 2 x square root (incidence) x (1 - incidence)
Plugging in the incidence of 1/4000, we get:
Carrier frequency = 2 x square root(1/4000) x (1 - 1/4000) = 1/32. 
Therefore, the best choice is B, 1/32.

Question 7

In a linkage analysis,given that you do not know the distance between a marker and the disease locus,the calculation is reiterated for many values of θ.How,then,is one LOD score selected from these data?

A) The lowest θ is chosen
B) The highest θ is chosen
C) The θ associated with the lowest LOD is chosen
D) The θ associated with the highest LOD is chosen
E) You must take into account information from surrounding markers

Accepted Answer

The LOD score is a measure of the likelihood of linkage between a marker and a disease locus, with higher LOD scores indicating stronger evidence for linkage. Therefore, the LOD score associated with the highest θ value (which represents the highest likelihood of no linkage) is chosen as the best estimate of the LOD score for that particular marker-disease pair. This is because the highest θ value represents the scenario in which the marker and disease locus are farthest apart on the chromosome, and if linkage is still detected at that distance, it is more likely to be real than if linkage is only detected at closer distances where recombination events are more frequent. Additionally, taking into account information from surrounding markers may help to confirm or refine the estimated θ value for the marker being analyzed, but the ultimate choice of LOD score is still based on the highest θ value tested.

Question 8

Which of the following can disturb Hardy-Weinberg equilibrium?&#10;A) Assortative mating&#10;B) Natural selection&#10;C) Population bottleneck&#10;D) A small population size&#10;E) All of the above

Accepted Answer

All options can disturb the Hardy-Weinberg equilibrium.

Assortative mating refers to the tendency of individuals with similar phenotypes to mate with each other more often than expected by chance. This can cause deviations from the expected genotype frequencies in the population.

Natural selection can favor certain traits over others, which can affect the frequency of alleles in a population. For example, if a certain phenotype confers a survival advantage, individuals with that phenotype may be more likely to reproduce and pass on their alleles.

A population bottleneck occurs when a significant portion of a population is removed due to a catastrophic event, such as a natural disaster or disease outbreak. This can reduce the genetic diversity of the population and cause deviations from the expected genotype frequencies.

A small population size can lead to genetic drift, which is the random fluctuation of allele frequencies due to chance events. This can cause the genotype frequencies to deviate from the expected values of the Hardy-Weinberg equilibrium.

Question 9

What has led to the rise in frequency of the alleles for the sickle cell trait?&#10;A) Genetic drift&#10;B) Population bottleneck&#10;C) Heterozygote advantage&#10;D) Negative selection&#10;E) Assortative mating

Accepted Answer

The rise in frequency of the sickle cell allele can be explained by the heterozygote advantage. Individuals who are heterozygous for the sickle cell allele have a better chance of survival in regions with high incidence of malaria, which creates a selection pressure for the allele to persist in the population.

Question 10

What is &#952; a measure of?&#10;A) Distance between genetic loci&#10;B) Natural selection&#10;C) Genetic drift&#10;D) Migration&#10;E) Genetic contribution to a trait

Accepted Answer

θ is a measure of the distance between genetic loci. It is used to quantify the level of recombination between loci on a chromosome.

Question 11

How is artificial selection against a genetic disorder predicted to affect the disease incidence in the autosomal dominant and autosomal recessive cases,respectively?&#10;A) Decrease rapidly, decrease rapidly&#10;B) Decrease rapidly, decrease slowly&#10;C) Decrease slowly, decrease rapidly&#10;D) Stay the same, decrease slowly&#10;E) Decrease slowly, stay the same

Accepted Answer

The answer of How is artificial selection against a genetic...

Question 12

What selective agent has resulted in heterozygote advantage for thalassemia mutation carriers?&#10;A) Influenza&#10;B) Plague&#10;C) Tuberculosis&#10;D) AIDS&#10;E) Falciparum malaria

Accepted Answer

The answer of What selective agent has resulted in heterozygote...

Question 13

How are the LOD scores from multiple affected families combined?&#10;A) Added&#10;B) Subtracted&#10;C) Averaged&#10;D) Multiplied&#10;E) They cannot be combined

Accepted Answer

The answer of How are the LOD scores from multiple...

Deck 8: Population and Mathematical Genetics