Question 1

Which of the following best explains why only a small percentage of the genetic basis of diseases has been identified through pedigree analysis?

Accepted Answer

Pedigree analysis is limited to monogenic diseases with large effect sizes and requires generational sequence data.

Question 2

In a trio study designed to identify de novo mutations, which individuals' genomes are compared?

Accepted Answer

Mother, father, and child.

Question 3

A de novo mutation occurs during which of the following processes?

Accepted Answer

Gametogenesis or embryonic development.

Question 4

Which equation best represents the expected rate of replication errors per nucleotide with proofreading?

Accepted Answer

$1 	imes 10^{-10}$

Question 5

Why are polygenic diseases difficult to study using pedigree analysis?

Accepted Answer

Each mutation has a small effect size and many genes are involved, making inheritance patterns complex.

Question 6

Which of the following is a major pitfall of GWAS studies related to population effects?

Accepted Answer

GWAS may mistakenly identify population-specific loci as causative for disease due to differences in allele frequency.

Question 7

In the context of linkage disequilibrium, what does it mean if marker alleles appear together in a disease population more than expected?

Accepted Answer

There is a non-random association between alleles at different loci, indicating linkage disequilibrium.

Question 8

A GWAS identifies allele rs1767474A as being associated with high cholesterol. What is the most appropriate interpretation for an individual who carries this allele?

Accepted Answer

The allele is associated with increased risk, but does not guarantee disease; clinical decisions should consider other risk factors.

Question 9

Which of the following best describes the difference between pedigree analysis and GWAS?

Accepted Answer

Pedigree analysis is used for rare, monogenic diseases with large effect sizes, while GWAS is used for common, polygenic diseases with small effect sizes.

Question 10

In a GWAS, what does a high $-\log_{10}(p)$ value on a Manhattan plot indicate?

Accepted Answer

A strong statistical association between the marker and the trait.

Question 11

Which scenario would most likely result in a mosaic de novo mutation?

Accepted Answer

A mutation occurs in a single cell during early embryonic development, leading to some cells carrying the mutation and others not.

Question 12

For a de novo recessive mutation to cause a phenotype, what must be true about the parents?

Accepted Answer

One parent must be heterozygous for the mutation, resulting in loss-of-heterozygosity (LOH) in the child.

Question 13

Which of the following is a key feature of polygenic traits?

Accepted Answer

They involve multiple genes, each contributing a small effect to the phenotype.

Question 14

In the wheat grain color example, what is the expected frequency of the genotype $AABB$ in the $F_2$ generation?

Accepted Answer

$1/16$

Question 15

Which variable should be excluded when designing a trio study to identify de novo mutations?

Accepted Answer

Environmental exposures after birth.

Question 16

Why is it important to compare the genome sequence of a child to both parents in trio studies?

Accepted Answer

To distinguish de novo mutations from inherited variants.

Question 17

Which of the following statements about GWAS is correct?

Accepted Answer

GWAS identifies genetic variants associated with disease risk, but does not prove causation.

Question 18

What is the main reason DNA polymorphisms are important in both pedigree and association analyses?

Accepted Answer

They serve as genetic markers to track inheritance and association with traits.

Question 19

Which of the following best describes the concept of additive alleles in polygenic inheritance?

Accepted Answer

Each allele contributes equally and independently to the phenotype.

Question 20

A GWAS for myopia identifies a chromosomal region with high-scoring markers. What is the next logical step in understanding the genetic basis of myopia?

Accepted Answer

Investigate the candidate genes in the region to determine their biological function and how they may contribute to the phenotype.

Human Genetic Experiments: Sep 29

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