L3 Nutritional Genomics

Question 1

Define nutrigenetics

Answer 1

How genetic variation can influence metabolism.

Question 2

Define nutrigenomics

Answer 2

How diet can influence gene expression (a change in phenotype without a change in geneotype). Also called epigenetics.

Question 3

What is transcription?

Answer 3

When DNA is copied into RNA.

Question 4

Difference between genotype and phenotype.

Answer 4

geneotype- the actual genetic variation.

phenotype - the expression of the geneotype (what we see).

Question 5

Sickle Cell Disease

Answer 5

A mutation in the bases in the DNA sequence which normally codes for glutamic acid but rather codes for valine. Hemoglobin doesn’t carry )2 efficiently and blood cells become sticky and clump together.

Question 6

Single nucelotide polymorphisms

Answer 6

A change in one base and may or may not have an effect on the protein function/expression.

Question 7

What is the enzyme that converts 5,10-methyleneTHF to 5-methylTHF?
How does the heterozygous variant effect the conversion?

Answer 7

MTHFR (methyleneTHF Reductase)

decreased conversion > need to increase folate intake.

Question 8

What is the difference between RDA and EAR?

Answer 8

RDA - amount to meet the needs of 97.5% of pop.

EAR - amount to meet 50% of pop.

Question 9

What is the Health Canada recommendation of folate intake for women who can become pregnant?

Answer 9

400ug of synthetic folic acid/day from multivitamin. (increase for women who have history of NTD’s)

Question 10

What is the gene that regulates lipid metabolism?

Answer 10

Sterol Response Element Binding Protein (SREBP-1c).

Question 11

How does a single nucleotide polymorphism affect the expression of the SREBP-1c gene (X3)?

Answer 11

Snp + a high fat diet will lead to an over expression of the gene meaning that it will increase fat metabolism (dyslipidemia), impaired glucose metabolsim, and type-2-diabetes.

Question 12

What variant of the gene that regulates lipoprotein-cholesterol clearance from plasma results in higher LDL levels when combined with a high fat diet?

Answer 12

Apolipoprotein E4

Question 13

What hormone inhibits muscle protein synthesis?
Which gene regulates the expression of this hormone?
Which variant results in a deletion of the gene and increased muscle synthesis?

Answer 13

myostatin
MSTN
mh/mh

Question 14

In Prader-Willi Syndrome, what gland is effected and how (X3)?
How does it effect physical and mental growth (X5)?

Answer 14

Hypothalamus - dysregulation of the growth hormone, hunger-satiety hormones, and other endocrine secretions.
Results in short stature, lower lean mass, hyperphagia (no satiety), and developmental delays.
All results in food seeking behaviours in early childhood.

Question 15

What dietary recommendation can you make for people with polymorphisms in the SREBP-1c gene and Apolipoprotein E4 gene?

Answer 15

Lower fat diets

Question 16

Explain what is meant by metabolic programming.

Answer 16

Non-genetic factors that cause a change in gene expression. These changes remain through cell divisions and allow for adaptations to the environment.

Question 17

What determines what genes are expressed?

Answer 17

The epigenetic code which is determined by the combination of DNA methylation and histone modifications.

Question 18

Does the methylation of DNA and the histone modification of a gene activate or inactivate the gene?

Answer 18

inactivate

Question 19

What are some environmental factors that can result in epigenetic changes (X9)?

Answer 19

Environmental toxins, diet, stress, exercise, smoking, alcohol, drugs, pathogens, weather.

Question 20

What are some of the mechanisms that result in epigenetic changes?

Answer 20

DNA methylation, histone modification, and chromatin remodeling.

Question 21

What are some of the changes in phenotype that can occur when epigenetic changes occur (X5)?

Answer 21

Physical shape, disease susceptibility, stress response, behaviour, longevity.

Question 22

Can epigenetic changed be reversed?

Answer 22

Unknown

Question 23

What is the Barker Hypothesis?

Answer 23

A.K.A. Deveopmental Origins of Disease Hypothesis
Suggests that the environment that a fetus is exposed to in the womb and in early life is strongly related to risk of chronic disease in adult life.

Question 24

In a study done in the UK, low birth weights are linked to mortality for people below 65 years old for what chronic disease?

Answer 24

Cardiovascular Disease

Question 25

SGA and LBW fetus and infants are at an increased risk for what chronic diseases (X6)?

Answer 25

Dyslipidemia, hypertension, glucose intolerance, CVD, T-2-D, obesity

Question 26

A LGA infant is at an increased risk for what chronic diseases (X4)?

Answer 26

Dyslipidemia, hypertension, glucose intolerance, obesity

Question 27

Pregnant women who were exposed to the Dutch Famine in late pregnancy had infants who grew up to have an increased risk of ____?

Answer 27

T-2-D: by measure of blood glucose

Question 28

Pregnant women who were exposed to the Dutch Famine in late and mid pregnancy had infants who grew up to have an increased risk of ____?

Answer 28

Microalbuminuria: by measure of albumin in urine

Question 29

Pregnant women who were exposed to the Dutch Famine in early pregnancy had infants who grew up to have an increased risk of ____?

Answer 29

Kidney dysfunction and CVD: by measure of LDL/HDL in blood, and CHD

Question 30

What 4 nutrients are involved in methyl-group metabolism?

Deficiency and supplementation can alter ____ and ____?

Answer 30

Choline, methionine, vitamin B12, and folate.

DNA and histone methylaton

Question 31

This nutrient deficiency has been associated with irreversible changes in brain structure and function.

Answer 31

Choline

Question 32

Protein deficiency during pregnancy is associated with what changes in the infant’s physical development and receptor expressions (X5)?

Answer 32

Pancreatic islet cells, GLUT4 expression, adipose tissue, heart tissue, and leptin regulation.

Question 33

In animal models, energy restrictions in-utero result in what changes in an infant? (X5)

Answer 33

• Liver and pancreatic cell differentiation (effect metabolism)
• Distribution of muscle cell type and muscle cell glucose transport (insulin sensitivity)
• Number of nephrons in kidney (regulate fluid and electrolyte balance)
• Endothelial function
• Bone density

Question 34

What is sarcopenia?

Answer 34

An aging condition that is strongly believed to start in fetal development and is associated with lean tissue and low muscle function.
Loss of lean muscle mass associated with aging.

Question 35

What are some of the adaptive responses that the body will do in an undernourished environment (X8)?

Answer 35

• Small birth size
• Premature birth
• Fetal sarcopenia
• Early puberty
• Altered HPA axis
• Altered behaviour
• Increased insulin resistance
• Propensity to store fat

Question 36

Explain the “Thrifty Phenotype Model”.

Answer 36

In fetal development, if nutrients are restricted, the growth slows and results in an SGA fetus as well as an adaptation of the phenotypes.
- In a postnatal environment that is nutrient poor, the thrifty phenotype is a survival advantage BUT in a postnatal environment that is nutrient rich, it can lead to a predisposition to chronic diseases (obesity, and metabolic syndrome).

Question 37

Does the father’s diet impact offspring health?

Answer 37

A restrictive protein diet in animal models from weaning to puberty resulted in the offspring having an increased gene expression for cholesterol/lipid synthesis.

Question 38

What is an HPA axis?

Answer 38

The interactions between the hypothalamus, pituitary gland, and the adrenal gland.