D2.2.10 Monozygotic twin studies Notes

Monozygotic Twin Studies Are A Unique Opportunity to Explore Environmental Impacts on Gene Expression

1. They share 100% of their DNA, making them ideal for studying the influence of the environment on gene expression.
2. This is because by comparing identical twins, scientists can isolate environmental effects from genetic ones.

Gene Expression and the Environment

1. Gene expression is the process by which information in DNA is used to produce proteins, which determine an organism's traits.
2. While the genetic code remains constant, the environment can influence which genes are active or inactive.

Mechanisms of Environmental Influence

1. Epigenetic Modifications:Chemical changes to DNA or histones that regulate gene activity without altering the genetic code.
   1. Examples include DNA methylation and histone acetylation.
2. Transcription Factors: Proteins that bind to DNA and control the transcription of specific genes.
   1. Environmental signals can activate or deactivate these proteins.
3. RNA Stability: Environmental factors can affect how long mRNA molecules persist, influencing protein production.

Long-Term Effects of Environmental Exposure

1. Lifestyle Choices: Diet, exercise, and smoking can lead to epigenetic changes that influence health outcomes.
2. Stress and Mental Health: Chronic stress can alter gene expression related to mood and cognition.
   1. Identical twins exposed to different stress levels may show varying susceptibility to mental health disorders.
3. Disease Susceptibility: Epigenetic changes can increase or decrease the risk of diseases like cancer or diabetes.

Limitations of Twin Studies

1. Sample Size: Identical twins are rare, limiting the number of participants in studies.
2. Complex Interactions: It can be challenging to separate the effects of specific environmental factors from genetic influences.
3. Generalizability: Findings from twin studies may not apply to the broader population.