Human Heredity, the Human Heredity, the Environment and Environment and
Disease: Nature Disease: Nature andand NurtureNurture
National Human Genome Research
Institute
National Institutes of
Health
U.S. Department of Health and
Human Services
Emily L. Harris, Ph.D., M.P.H.Epidemiologist, Office of Population GenomicsNational Human Genome Research Institute
May 1, 2007
Nature and Nurture:Nature and Nurture:
Causal models & inferences from studying populations
Genes (or nature)
Environment (or nurture)
A Continuum of Causation
AND
Height
Nature and Nurture:Nature and Nurture:
Causal models & inferences fromstudying populations
Question: What causes the differences in height among individuals?
AND
Height
AND
Nutrition (environment)
Height
AND
Height
AND
Genes
Height
AND
Height
AND
Height
Genes & Environment
Nature and Nurture:Nature and Nurture:
Causal models & inferences fromstudying populations
Question: What causes the differences in height among individuals?
Conclusion: Depends on the population(s) studied.
Nature and Nurture:Nature and Nurture:
Multifactorial models incomplex diseases
Example: Cancer
a
R
Most Cancer Is NOT Inherited
Known Inherited Factor
All Breast Cancer Patients
Unknown Factor(s)
a
R
Chemical Bases in DNA
DNA molecule (chromosome)
Chemical bases
Gene
AT
CG
a
R
Altered DNA->Altered Protein
NucleusDNA
Protein
Chain of amino acids
Ribosome
Gene
DNA bases mRNA
Cell membrane
a
R
Many Mutations Lead to Cancer
Malignant Cells
NormalCell
FirstMutation
SecondMutation
ThirdMutation
Fourth orLater
Mutation
a
R
Most Cancer Is NOT Inherited
Known Inherited Factor
All Breast Cancer Patients
Unknown Factor(s)
Factors affectingFactors affectingCancer Development & Cancer Development &
ProgressionProgression Oncogenes (cancer promoting)Oncogenes (cancer promoting) Tumor suppressor genesTumor suppressor genes Carcinogen metabolism genesCarcinogen metabolism genes Immune surveillance for abnormal Immune surveillance for abnormal
cellscells
Some Factors affectingSome Factors affectingCancer Development & Cancer Development &
ProgressionProgression Oncogenes (cancer promoting)Oncogenes (cancer promoting) Tumor suppressor genesTumor suppressor genes
E.g., DNA repair proficiencyE.g., DNA repair proficiency Carcinogen metabolism genesCarcinogen metabolism genes Immune surveillance for abnormal Immune surveillance for abnormal
cellscells
DNA Repair & Cell PathologyDNA Repair & Cell Pathology
Author: Harold Brenner
Lifespan-influencing GenesLifespan-influencing Genes& DNA Repair& DNA Repair
Author: Harold Brenner
Genes (or nature)
Environment (or nurture)
A Continuum of Causation
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