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Flashcards in Bemis: Nutrigenomics Deck (22):

What is nutrigenetics?

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.


What are the majority of nutrigenetic gene variants?

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


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



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

Is a SNP a mutation?

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.


What is the purpose of a nutrigenetic study?

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.


What are examples of Nutrigenetics?

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


What is the benefit of nutrigenetics?

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)


What tools are used to discover new gene environmental interactions?

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


How are the genes of interest discovered?

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.


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

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)


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

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


What does it mean if a SNP is sufficient?

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)


What is nutrigenomics?

Identifying environmental factors that effect gene expression


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

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

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


What technology is used for nutrigenomics?

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


What is nutritional epigenetics?

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.


What are examples of chemical tags that alter gene expression?

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


What are the benefits of nutritional epigenetics?

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.


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


The diet of one generation may impact the next.


What is nutritional genomics?

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.


What technology is used to detect nutritional epigenetics?

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


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

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