Nutritional Genomics - Bemis Flashcards
What are the three sub-disciplines of nutritional genomics?
- Nutrigenetics
- Nutrigenomics
- Nutritional epigenetics
What does nutritional genomics mean?
- Gene – environment interactions that may be managed to prevent diet related disease
- e.g. gene-environment interactions in the Cytochrome P450 family and specific therapeutics
- Understanding single gene function and the direct relationship to nutrients and the larger impact on disease
- This is becoming a new medical discipline.
What is nutrigenetics?
- Refers to functional changes in the nucleic acid code that influences a persons response to nutrients
- genetice: individual SNP
- Variation in genes occurs over evolutionary time and results in gene variants that may make a gene more functional or less
- Variation may be associated with geographic ancestry
- A gene variant may allow the better use of a specific nutrient by the organism
What is the goal in nutrigenetic studies?
Seek to identify functional outcome of a change in the nucleic acid code (variant) usually a SNP that results in a change in the response to a nutrient
What are variants?
- Variants are also called alleles
- The majority of variants are at a single DNA base
- When the variant occurs in a population it is called a single nucleotide polymorphisms (SNPs)
- Technically all SNPs or variants are mutations but mutation is usually reserved for a genetic change with deleterious consequences.
What are some examples of Nutrigenetics?
- Paul’s genotype is an example of nutrigenetics C282Y mutation in HFE gene contributes to hemochromatosis
- Lactose intolerance is the norm in adulthood but due to a SNP in the LCT gene many Caucasians of northern European descent are able to keep making lactase and breaking down lactose
- Celiac disease is genetically determined but environmentally triggered
What are the potential benefits of Nutrigenetics?
- The benefit to patients is that it would be possible to know in advance that a person is at risk of a potentially fatal anaphylaxis
- or that the physician may tailor treatment to the individuals metabolic capability
- May help the physician to confirm suspected dietary conditions, such as lactose intolerance, Celiac disease, Hemochromatosis
What tools are used to discover new gene – environmental interactions? How are the genes of interest discovered?
- Deep sequencing
- study the mechanism of how genes and environment interact
-
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
- LARGE amount of data for numerous people
What does Necessary and Sufficient mean in terms of a SNP found through Nutrigenetics?
- Biochemical and Physiological confirmation that the SNP is required (necessary) by itself (sufficient) to cause the change in phenotype
- If a SNP (or variant) is necessary (required) but not sufficient it would mean that it is always present but is not the only requirement for the condition.
- Sufficient means that the SNP (or variant) is the actual cause of the condition,
- could also be assisted by other SNPs in the same gene or in another location, which might modulate its behavior in a positive or negative manner.
What is Nutritional Genomics?
environmental factors that effect gene expression (may be multiple genes)
What is the goal of Nutrigenomics?
- Seeks to identify environmental factors that effect gene expression (global gene expression/or single gene variants)
- The goal is to use food in a targeted fashion rather than just use food to supply the raw materials for cellular function.
- An example is to use more omega-3 fats to reduce gene expression of inflammatory cytokines
- Public Health messages
What are the benefits of Nutritional Genomics?
- There maybe dietary factors such as cruciferous vegetables (broccoli etc) that circumvent certain limitations caused by common gene variants
- These dietary changes may be possible to implement across the spectrum if the response is highly prevalent in a population
What toos are used in Nutrigenomics?
- Commonly the microArray
- Exome sequencing
- Deep sequencing (the only method to identify most RNAs)
- Bioinformatic Analysis
What is Nutritional Epigenetics?
- Changes in gene expression that does not involve changes in nucleotide sequence
- Chemical tags are put on the DNA sequence or on proteins such that expression from the genome is altered
- Include methylation of DNA and acetylation of proteins
- Methylation occurs at cytosine residues often preventing gene expression
- Acetylation is the addition of acetyl groups to the histone proteins keeping DNA closed or opened for translation
What is the carrier frequency?
- How often the allele (variant) occurs in a population
- Variation in a population may influence health care policy and medical practice
- PKU as an example: screening occurs in all newborns, states regulate screening