Genes vs. Environment

(Nature vs. Nurture)

Is everything determined by genetics?

• Your characteristics (phenotype) are often a combination of your genotype (genetics) and your environment.

• Both play an interactive role in determining your health.

• Examples…

1. Sickle Cell Anemia

SCA is a serious (sometimes deadly) genetic disease, but having SCA or being a carrier for SCA is an advantage against malaria (a communicable disease).

*Recall that a single base change in the gene (DNA sequence) that codes for hemoglobin causes this. Hemoglobin will clump together inside red blood cells, giving them a sickle shape, which is more likely to clot.

Sickle Cell Anemia

• Sickle Cell is more common among African Americans.

• Prognosis: patient can live normal life if treated

• Sickle Cell is most common in parts of Africa, South and Central America. Why?– Higher incidence of malaria

due to greater number of mosquitos carrying malaria parasite

– Malaria parasite cannot live inside sickle cells.

Malaria

• Caused by a parasite passed into the blood by mosquitoes

• Symptoms:– Flu-like symptoms– Elevated temp., mild jaundice, enlarged

spleen– Severe form of disease: organ distress and

failure, which can lead to death (It’s an example of pleiotropy- where one gene affects more than one trait.)

2. Lung & Mouth Cancer

There are mutant genes that make you more likely to get certain cancers, but…

Lung/mouth cancer is most likely caused by prolonged exposure to tobacco products. These products damage DNA to cause uncontrolled cell growth.

Lung & Mouth Cancer

Lung & Mouth Cancer

Healthy lung Cancerous lung

Lung & Mouth Cancer

Lung & Mouth Cancer

3. Skin cancer/sun exposure/folic acid/vitamin D

Some people are genetically more susceptible to skin cancer- light-skinned.

Environmentally, increased sun exposure increases the risk of skin cancer.

*UV radiation from tanning beds also increases the risk! New FDA regulations may be introduced soon for tanning teens! (WHO found skin cancer 75% more likely in people who use tanning beds in teens and 20s!)

Skin Cancer & Sun Exposure

Consuming folic acid (dark green leafy vegetables, dried beans and peas, vitamins) reduces your sensitivity to sun.

Sun exposure causes the skin to produce Vitamin D. Vitamin D can prevent or treat many types of cancer, including skin cancer. So, 15 min. of mild sun exposure a few times each week may be good for you!

Sun Exposure & Vitamin DDarker skinned people have

an advantage in equatorial regions- they’re more resistant to UV rays. But…

Dark skinned people who live in cloudier regions north of the equator need to make sure they also get enough Vitamin D to make up for the lack of it due to less sun exposure or they will get Rickets!

One way to supplement it is by buying Vitamin D milk!

4. Diabetes/Diet/Exercise

Diabetes Types 1 and 2 are both genetic disorders.

Type 1 is called juvenvile or insulin-dependent diabetes. The lack of insulin production has very little to do with environment.

DiabetesType 2 usually occurs after

age 40 and its onset is usually brought on by obesity. It can be controlled by proper diet and exercise.

Uncontrolled diabetes can result in:

Blindness, heart disease, circulation problems, slowness to heal, and amputation of limbs.

Diabetes

• Symptoms of type 2 include frequent urination, thirst, hunger, and weight loss.

• Type 2 is PREVENTABLE! Eat healthy, exercise, and maintain a healthy weight.

Atherosclerosis (heart disease)

5. PKU and diet

PKU is a recessive genetic disorder that can cause mental retardation. However, symptoms of PKU can be controlled or eliminated by giving the baby a diet low in protein-rich foods (milk, eggs, meat, nuts, other high-protein foods, etc.)

*Doctors test for this at birth, so parents know right away if their kid has it.

PKU patients must avoid these

PKU patients may have these