Polygenic, Quantitative, and Multifactorial Inheritance

polygenic traits

traits controlled by 2+ genes (nearly every phenotype influence by 2+ genes)

multifactorial traits

polygenic traits (controlled by 2+ genes) with an environmental factor (almost all traits are this)

common properties of all systems

nodes, linked components (edges), hubs, connectors

normal distribution (bell curve)

polygenic traits in a population

hormones (hGH), nutrition

environmental and metabolic factors affecting height (for multifactorial traits)

factors affect flowering time (multifactorial trait)

• temp, day-length, nutrition, drought (environmental control)

• repressors block floral transition, juvenile phase length regulated (developmental control)

process to determine genetic and physiological basis of trait variation

genetic map, associate genotype with phenotype, conduct quantitative trait locus (QTL) analysis

obesity

• mutations in ob gene in mouse (produces leptin hormone produced in fat cells) cause ___

• human equivalent gene is on chromosome 7

• complex disorder involving multiple genes and environmental interactions

obesity (it drives up cost of healthcare paid by everyone)

Michael Bloomberg says gov’t should regulate size of sodas to reduce ____

autonomy, beneficience, non-maleficience, justice

would it be ethical to require people with alleles that increase their probability of obesity to exercise more/take drugs to prevent expression of condition in order to reduce healthcare costs?

ethical principles?

spina bifida

• neural tube defect in first month of embryonic development

• nervous system damage is permanent → paralysis and learning disabilities

• no cure

• multifactorial trait (higher risk of having 2nd child w SB, affected by folic acid deficiencies in mother)

autonomy, beneficience, nonmaleficence, justice

• folic acid deficiency in mother is associated with baby born with neural tube defect (spina bifida)

• not fully understood how folic acid interacts w genes involved in neural tube formation

• should mom be forced by doctors/state to take folic acid?

• is it ethical for mom to not take folic acid?

ethical principles involved?

a (no legal basis for intervention until after birth currently)

law allows physicians to go to court for which scenario?

a. parent refuses treatment for babies to reduce harm and improve health

b. parent refuses treatment/supplement to reduce the probability of injury to fetus