PBL Genetics and Epidemiology

Question 1

What is Allelic heterogeneity?

Answer 1

It is thought that asthma is not a single disease, but rather a complex series of genes and presenting phenotypes.
–> this results in each individual having a different interaction with the same environment.

Question 2

What is an example of Allelic heterogeneity in asthma?

Answer 2

Two people with asthma may be exposed to the same irritants their entire life, but the difference in their genetics, alleles, and expressed phenotype results in varying degrees of symptom presentation.

Question 3

What genetic cause of asthma is supported by a lot of data?

Answer 3

Asthma susceptibility based on polymorphisms of 17q21.

Question 4

What environmental factors lead to asthma?

Answer 4

Indoor air pollution plays a big role in causing asthma. Common indoor pollutants include:

• Cigarette smoke
• Mold
• Fumes from cleaning detergents
• Paints
• Sulfur dioxide
• NO
• Ozone
• Cold temperatures
• High humidity increases the chance of triggering asthma

Question 5

What is a primary source of indoor NO?

Answer 5

Gas stoves
–> studies suggest that people who cook with gas stoves are more prone to asthma attacks than those who use electric stoves.

Question 6

How does cigarette smoke relate to asthma?

Answer 6

Several studies show a strong correlation between smoking and developing asthma. This includes exposure to second hand smoke, especially as a child.
–> Smoking during pregnancy lowers lung function of the embryo and can increase chances of a premature birth, which is also a risk factor for asthma

Question 7

How does obesity relate to asthma?

Answer 7

Studies have provided date to show a strong link between being overweight and prevalence of having asthma. This is in both children and adults.

Question 8

What are Modifier genes?

Answer 8

These are genes that instead of masking other genes, they result in increased or decreased expression/modification of a second gene.
–> Genes that have small quantitative effects on level of expression of another gene

Question 9

What is the prevalence of asthma in the US? What causes this?

Answer 9

8. 2% prevalence (rising!)
   - Probably linked to obesity increase (but really, we don’t have a good explanation. Some cite the hygiene hypothesis: sterile environments as children don’t allow our immune system to distinguish non-harmful environmental antigens. But this might be more true for allergies than asthma.

Question 10

What are asthma risk factors?

Answer 10

1. Wheezing before age 3, allergic rhinitis, lower RTI’s early in life
2. NSAID-induced
3. Obesity, environmental tobacco smoke, residential exposures (pets, gas cooking, damp housing, mold) –> all socioeconomic problems for lower class

Question 11

What system causes bronchoconstriction?

Answer 11

Parasympathetics

Question 12

What is the Methylcholine challenge test?

Answer 12

It is a test that uses acetylcholine analog at a low level that would not affect someone with normal lung function, but would aggravate asthma patients

Question 13

What races have the highest risk of asthma?

Answer 13

Highest: Puerto RIcan, Black, Mixed Race
Lowest: Asian