CDN Nutritional Genomics & Precision 5 — Questions and Answers
Question 1: Which concept describes the phenomenon where identical twins show diverging health outcomes over time due to differing epigenetic changes?
- Genetic penetrance
- Epigenetic drift (Correct answer)
- Genomic imprinting
- Linkage disequilibrium
Correct answer: Epigenetic drift
Epigenetic drift refers to the accumulation of methylation and histone modification differences over time due to environmental exposures including diet.
Question 2: A dietitian using a 'precision nutrition' approach would most appropriately integrate which combination of data to personalize dietary recommendations?
- Genetic variants alone
- Dietary recall only
- Genotype, phenotype, microbiome, and lifestyle data (Correct answer)
- BMI and waist circumference only
Correct answer: Genotype, phenotype, microbiome, and lifestyle data
Precision nutrition synthesizes multi-omics data—genomic, metabolomic, microbiomic, and phenotypic—to generate individualized dietary guidance beyond population-level recommendations.
Question 3: Genomic imprinting refers to which epigenetic mechanism?
- Equal expression of both parental alleles
- Parent-of-origin-specific gene expression based on epigenetic marks (Correct answer)
- Random X chromosome inactivation in females
- Somatic mutation accumulation in aging cells
Correct answer: Parent-of-origin-specific gene expression based on epigenetic marks
Genomic imprinting silences one parental allele through methylation, so only the maternal or paternal copy is expressed depending on the gene.
Question 4: Which dietary component is most studied for its ability to influence DNA methylation through the one-carbon metabolism pathway?
- Vitamin C
- Methyl-donor nutrients (folate, B12, choline, methionine) (Correct answer)
- Vitamin E
- Calcium
Correct answer: Methyl-donor nutrients (folate, B12, choline, methionine)
Methyl-donor nutrients supply the methyl groups used by DNA methyltransferases to methylate cytosine residues, directly modulating epigenetic patterns.
Question 5: The gut microbiome influences host gene expression primarily through which mechanism relevant to nutritional genomics?
- Direct integration of bacterial DNA into host chromosomes
- Production of metabolites like SCFAs that act as epigenetic modifiers (Correct answer)
- Synthesis of host structural proteins
- Elimination of dietary antioxidants before absorption
Correct answer: Production of metabolites like SCFAs that act as epigenetic modifiers
Microbial metabolites such as butyrate, propionate, and acetate modulate host histone acetylation and DNA methylation, linking diet, microbiome, and epigenome.
Question 6: When interpreting direct-to-consumer genetic test results for a client, a CDN's most important ethical responsibility is:
- Recommending supplements for every identified risk allele
- Contextualizing results within overall health data while avoiding genetic determinism (Correct answer)
- Dismissing all DTC genetic data as unreliable
- Ordering repeat genetic tests through clinical labs only
Correct answer: Contextualizing results within overall health data while avoiding genetic determinism
Ethical precision nutrition practice requires contextualizing genetic findings within the full clinical picture and avoiding overstatement of genetic risk, which can cause unnecessary anxiety.
Question 7: The 'thrifty gene hypothesis' proposed by Neel (1962) is most relevant to modern nutritional genomics in explaining:
- Why vitamin deficiencies are more common in women
- Genetic predisposition to obesity and type 2 diabetes in populations with historically feast-famine cycles (Correct answer)
- The adaptive benefits of lactase persistence in Northern Europe
- How omega-3 genes evolved in coastal populations
Correct answer: Genetic predisposition to obesity and type 2 diabetes in populations with historically feast-famine cycles
The thrifty gene hypothesis proposes that alleles favoring energy storage were advantageous during food scarcity but now promote obesity and T2DM in environments with continuous food abundance.
CDN Nutritional Genomics & Precision 5
Which concept describes the phenomenon where identical twins show diverging health outcomes over time due to differing epigenetic changes?