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General cognitive ability

Q: Human epigenome research two distinct fields

Epigenome mapping projects Goal --> creating extensive maps (reference epigenomics) of different cell types in the human body, at different stages of development --> Which genes are expressed in which cells and which genes contain epigenetic modifications in which cells? Which reions are transcribed in the brain --> Transcriptome. Which regions are methylated in the brain --> Methylome. Epigenome wide association studies & Transcriptome wide association studies. Goal --> Identify epigenetic mechanisms associated with a trait, disease or environmental exposure.

Q: SNPS IDENTIFIED IN GWAS OF COMPLEX TRAITS/DISEASE/ BEHAVIOR

--> 90% OF THE SNPS ARE LOCATED IN NONCODING DNA --> DNA that does not code for protein. These snps influence gene expression rather than protein structure/function The effect is often in a specific tissue. Example --> Expression RNA of genes that influence major depression risk. Most important SNPs that are associated with depression were expressed most in the brain.

6 important questions on General cognitive ability

Concordance rate mx twinst

If you look at the concordance rate of MZ for several diseases, you can see that the concordance rate for some traits as autism is very high (93,7) (diabetis type 1 42,9) but for other traits it is much lower parkinson 15%. This means that not the genes alone determines whether you get a disease or not.
Of course, there are also unique environmental influences because the mz don't share the exact same environment that can explain the differences in disease but there can also be epigenetic influences.

Human epigenome research two distinct fields

Epigenome mapping projects
Goal --> creating extensive maps (reference epigenomics) of different cell types in the human body, at different stages of development --> Which genes are expressed in which cells and which genes contain epigenetic modifications in which cells?
Which reions are transcribed in the brain --> Transcriptome.
Which regions are methylated in the brain --> Methylome.

Epigenome wide association studies & Transcriptome wide association studies.
Goal --> Identify epigenetic mechanisms associated with a trait, disease or environmental exposure.

SNPS IDENTIFIED IN GWAS OF COMPLEX TRAITS/DISEASE/ BEHAVIOR

--> 90% OF THE SNPS ARE LOCATED IN NONCODING DNA --> DNA that does not code for protein.
These snps influence gene expression rather than protein structure/function
The effect is often in a specific tissue.
Example --> Expression RNA of genes that influence major depression risk.
Most important SNPs that are associated with depression were expressed most in the brain.

Similar studies have been preformed in monkeys

Studying monkeys who were reared by their mother and monkeys who were separated from their mother and compared the brains of the monkeys to look at DNA methylation and differences in gene expression.
Maternal rearing affects DNA methylation --> Monkey babies who are separated from their mother become anxious and aggressive and many of their genes are differentially methylated.
Early life experiences --> Epigenetic changes (DNA methylation) --> Long term gene expression change --> Behaviro later in life.

Epigenetics studies for MZ twins

MZ twins --> Ideal for studying epigenetic mechanisms.
Compare DNA methylation patterns of phenotypically discordant MZ twins.
Discordant --> One of the two has a disease/trait/behavior and the other one doesn't have it.
This design rules out many other possible explanations for why one person is aggressive: MZ twins have the same sex, age, DNA sequence and grow up in very similar environments.
MZ twins are not epigenetically identical --> What are the possible causes?
Identical twins always have a unique environment that can cause differences in DNA methylation.
Dna methylation happens partly at random.