Question 1

What is the major locus contributing to type 1 diabetes?&#10;A) HNF1A&#10;B) CARD15&#10;C) HLA&#10;D) TCF7L2&#10;E) APOE

Accepted Answer

HLA (human leukocyte antigen) is the major locus contributing to type 1 diabetes, with specific alleles of HLA class II genes being strongly associated with the disease. Other loci, such as INS (insulin) and PTPN22 (protein tyrosine phosphatase, non-receptor type 22), also contribute to susceptibility to the disease, but HLA is the most significant contributor. The other options listed are not major contributors to type 1 diabetes susceptibility, although some of them may be associated with other types of diabetes or other conditions.

Question 2

One could best tease apart the genetic and environmental causes of a trait through comparisons of which of the following groups?&#10;A) First-degree relatives versus second-degree relatives&#10;B) Sisters versus brothers&#10;C) Monozygotic versus dizygotic twins&#10;D) Parents versus children&#10;E) Twins versus siblings

Accepted Answer

By comparing the similarities between monozygotic twins, who share 100% of their genetic material, and dizygotic twins, who share only 50% of their genetic material on average, we can determine the extent to which genes contribute to a trait. Differences between identical twins must therefore be due to environmental factors.

Question 3

The gene on chromosome 21 encoding which protein is thought to contribute to the increased risk of Alzheimer's disease in individuals with Down syndrome?&#10;A) Presenilin 1&#10;B) Presenilin 2&#10;C) Amyloid precursor protein&#10;D) Alpha-synuclein&#10;E) Parkin

Accepted Answer

The gene on chromosome 21 that encodes the Amyloid precursor protein (APP) is known to be overexpressed in individuals with Down syndrome. The increased production of APP leads to an accumulation of beta-amyloid plaques in the brain, a hallmark feature of Alzheimer's disease.

Question 4

Why is population genetic screening for hemochromatosis not recommended?&#10;A) The low frequency of carriers&#10;B) No treatment is available&#10;C) High allelic heterogeneity&#10;D) Because it manifests only late it life&#10;E) Low penetrance of the mutations

Accepted Answer

The low penetrance of the mutations means that not all individuals with the genetic mutation will develop the disease, making widespread screening less effective.

Question 5

If a migrant group moves from an area with a low incidence of a particular disease to an area with a high incidence of that disease and the disease incidence in that group subsequently increases to match the incidence in the second location,what does this suggest about the disease etiology?

A) It is mostly genetic
B) It is mostly environmental
C) It is caused by both genetic and environmental factors
D) It is caused by food
E) Further research needs to be done

Accepted Answer

This suggests that the disease etiology is mostly environmental, as the increase in incidence corresponds with the movement to a new location. If it were mostly genetic, the incidence would not be expected to increase simply by moving to a new location. Additionally, if it were caused by factors such as food, this should not be affected by migration to a new location. However, it is possible that there is an interaction between genetic and environmental factors contributing to the higher incidence. Further research may be needed to fully understand the relationship between location, genetics, and disease incidence.

Question 6

The Factor V Leiden mutation is associated with:&#10;A)Reduced cleavage of Factor V by Protein C&#10;B) A low carrier frequency&#10;C) Decreased clotting&#10;D) Resolution of phenotype during puberty&#10;E) Delayed presentation due to fetal hemoglobin expression

Accepted Answer

The Factor V Leiden mutation results in reduced cleavage of Factor V by Protein C, leading to an increased risk of thrombosis.

Question 7

Which of the following classes of proteins has been associated with several genetic forms of epilepsy?&#10;A) Transcription factors&#10;B) Chaperones&#10;C) Mitochondrial proteins&#10;D) Ion channels&#10;E) Growth factor receptors

Accepted Answer

Ion channels are proteins that are responsible for the regulation of ion flow across the cell membrane. Several genetic forms of epilepsy have been associated with mutations in ion channel genes, disrupting the balance of ions and leading to abnormal neuronal excitability and seizures.

Deck 15: Genetic Factors in Common Diseases