Nutritional Genomics - Bemis

Question 1

What are the three sub-disciplines of nutritional genomics?

Answer 1

1. Nutrigenetics
2. Nutrigenomics
3. Nutritional epigenetics

Question 2

What does nutritional genomics mean?

Answer 2

• 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.

Question 3

What is nutrigenetics?

Answer 3

• 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

Question 4

What is the goal in nutrigenetic studies?

Answer 4

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

Question 5

What are variants?

Answer 5

• 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.

Question 6

What are some examples of Nutrigenetics?

Answer 6

• 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

Question 7

What are the potential benefits of Nutrigenetics?

Answer 7

• 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

Question 8

What tools are used to discover new gene – environmental interactions? How are the genes of interest discovered?

Answer 8

• 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

Question 9

What does Necessary and Sufficient mean in terms of a SNP found through Nutrigenetics?

Answer 9

• 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.

Question 10

What is Nutritional Genomics?

Answer 10

environmental factors that effect gene expression (may be multiple genes)

Question 11

What is the goal of Nutrigenomics?

Answer 11

• 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

Question 12

What are the benefits of Nutritional Genomics?

Answer 12

• 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

Question 13

What toos are used in Nutrigenomics?

Answer 13

• Commonly the microArray
• Exome sequencing
• Deep sequencing (the only method to identify most RNAs)
• Bioinformatic Analysis

Question 14

What is Nutritional Epigenetics?

Answer 14

• 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

Question 15

What is the carrier frequency?

Answer 15

• 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