You have collected genomic DNA from 248 individuals with a particular disease (cases) and from 246 healthy individuals (controls), who are matched on age and sex to help avoid confounding factors. You have decided to screen for mutations in a candidate gene X, which is involved in some biological aspect of the disease, and you have identified ten polymorphic loci within the gene, three are in the promoter region, three are within exons but are synonymous, two are intronic, and one is exonic and causes a non-synonymous amino-acid substitution. For the latter, you find that the usual nucleotide T is often replaced by C and therefore you are suspicious that there is a significant association.

Cases (ill) Control (healthy) Total
C (polym.) A = 332 B = 230 562
T C = 164 D = 262 426
Total 496 492 988

a. Calculate the odds of carrying a C for each group.
b. Calculate the odds ratio.
c. Do you think that carrying a C in the non-synonymous SNP under study predisposes the individual to disease Y?