Bemis: Nutrigenomics

Question 1

What is nutrigenetics?

Answer 1

A change in the nucleic acid code that influences a persons response to nutrients.

Gene variation can occur over time and make a gene more or less functional. A gene variant may allow BETTER or worse use of a specific nutrient.

Question 2

What are the majority of nutrigenetic gene variants?

Answer 2

Gene variants, also referred to as alleles, are usually a single DNA base.

Question 3

What is a variant called when it occurs in a population? (Nutrigenetics)

Answer 3

SNP

Question 4

People commonly say “he has an HFE gene mutation”. What is wrong with this statement?

Is a SNP a mutation?

Answer 4

We all have an HFE gene, but he carries a SNP that makes him at higher risk for accumulating iron and eventually developing Hemochromatosis

Technically yes, but mutation is usually reserved for a genetic change with a deleterious consequence.

Question 5

What is the purpose of a nutrigenetic study?

Answer 5

Identify the functional outcome of a change in the nucleic acid code (variant).

Identify a SNP that leads to a change in the response to a nutrient.

Question 6

What are examples of Nutrigenetics?

Answer 6

1. C282Y mutation in HFE gene contributes to hemochromatosis
2. Lactose intolerance is norm in adulthood but d/t a SNP in the LCT gene caucasians of N. European descent are able to keep making lactase and break down lactose.
3. Celiac diseases–genetically determined but environmentally triggered

Question 7

What is the benefit of nutrigenetics?

Answer 7

1. Know in advance a pt is at risk for a fatal anaphylaxis
2. Physician can tailor treatment to pt’s metabolic capability
3. help physician to determine suspected dietary conditions (lactose intolerance, celiac disease, hemochromatosis)

Question 8

What tools are used to discover new gene environmental interactions?

Answer 8

(DEEP SEQUENCING) illumina, 454, Solexa, RNAseq (transcriptome)

Question 9

How are the genes of interest discovered?

Answer 9

GWAS a genome-wide association study study of many different individuals to see if any variant is associated with a trait.

By function, regulation, co-expression, location in the genome.

Question 10

In nutrigenetics, how are SNPs in a location of a genome identified and linked to a nutrient?

Answer 10

1. Large population studies determine if many individuals have a specific SNP
2. Biochemical and physiological confirmation that an SNP is required by itself to cause the change in phenotype
3. Necessary and sufficient (sometimes you’ll have a gene that’s necessary, but it’s not sufficient to cause the disease)

Question 11

What does it mean if a SNP is necessary but NOT sufficient?

Answer 11

The SNP is ALWAYS present but not the only requirement for the condition.

Question 12

What does it mean if a SNP is sufficient?

Answer 12

The SNP is the actual cause of the condition (other SNPs in the same location may modulate its behavior in a pos or neg manner)

Question 13

What is nutrigenomics?

Answer 13

Identifying environmental factors that effect gene expression

Question 14

What is the goal of nutrigenomics and what is the example of this?

Answer 14

Use food to target/change cellular fxn. *Public health messages

ex- use more omega 3 fats to reduce gene expression of inflammatory cytokines

Question 15

What technology is used for nutrigenomics?

Answer 15

MicroArray
exome sequencing
deep sequencing (only method to identify most RNAs)
Bioinformatic analysis

Question 16

What is nutritional epigenetics?

Answer 16

Changes in gene expression that don’t involve changes in nucleotide sequence, but instead are caused by chemical tags that are put on the DNA sequence or on proteins that alter genome expression.

Question 17

What are examples of chemical tags that alter gene expression?

Answer 17

methylation of DNA and acetylation of proteins

1. methylation of cytosine residues–> prevents gene expression
2. Acetylation–addition of acetyl groups to histone PROTEINS keeps DNA closed or open for translation

Question 18

What are the benefits of nutritional epigenetics?

Answer 18

The chemical tags (methyl and acetyl groups) come from the diet so it may be easier to adjust the diet to better regulate these processes.

Regulate gene patterning in development, cellular differentiation and maintain gene expression.

Question 19

Can chemical tags be passed down to the next generation? Why is this significant?

Answer 19

Yes!

The diet of one generation may impact the next.

Question 20

What is nutritional genomics?

Answer 20

Gene – environment interactions that may be managed to prevent diet related disease
Another example of gene-environment interactions is the Cytochrome P450 family and specific therapeutics

Understanding single gene function and the direct relationship to nutrients and the larger impact on disease (celiacs)

This is becoming a new medical discipline.

Question 21

What technology is used to detect nutritional epigenetics?

Answer 21

1. Detect acetylation w/ an Ab directed against hte protein modificaiton
2. Methylation studies- bisulfite tx converts unmethylated cyosines but not methylated cyosines to uracil

Question 22

How can variation in a population influence health care policy and medical practice?

Answer 22

Carrier frequency – how often the allele (variant) occurs in a population

PKU as an example–can be fixed by changing the diet of individuals w/ the mutation

1. Screening occurs in all newborns
2. States regulate screening
3. All PKU patients should have genetic testing