You are studying a disorder that is based on the genetic composition at three loci. assume that a dominant allele at any locus adds 6 units of risk for the disorder and that a recessive allele at any locus adds 2 units of risk for the disorder. individuals with 29 or more units of risk develop the disorder. the environment does not affect the presence or absence of this disorder. how many risk units will be present in an individual of genotype aabbcc?

28 risk units

Explanation:

This is a classic case of quantitative genetics. The trait is not controlled discretely by dominant and recessive allele and rather shows a "continuous" effect. Such a trait is usually controlled by multiple genes. Each allele adds something to the trait and contribution by dominant allele is more than the contribution by recessive allele.

Here, dominant allele adds 6 units of risk and recessive allele adds 2 units of risk for the disorder. Three genes control the disorder phenotype. An individual with AABbCc genotype has four dominant alleles (AABC) and two recessive alleles (bc) hence the total risk units for this person will be:

(4 *6) + (2*2) = 24 + 4 = 28 units

cancer   is   essentially   uncontrolled   mitosis   of specialized cells

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."