Question

DA Schaumberg and colleagues studied the relationship of genetic variants in the retinoic acid receptor-related orphan receptor α gene (RORA) and the occurrence of age-related macular degeneration (Arch Ophthalmol 2010). Among 474 control subjects free of age-related macular degeneration, 130 had 2 copies of the G allele of 1 single nucleotide polymorphism (SNP) rs12900948 (G homozygotes), 128 had 2 copies of the A allele (A homozygotes) and the other 216 had 1 copy of each (heterozygotes). Among the 163 cases with age-related macular degeneration, 70 had 2 copies of the G allele (G homozygotes), 24 had 2 copies of the A allele (A homozygotes), and the other 69 had 1 copy of each (heterozygotes). The data is summarized in the 3×2 table below.

	Age-related Macular Degeneration
# of allels	Case	Control
0	24	128
1	69	216
1	70	130

a. Are the number of G alleles and occurrence of age-related macular degeneration associated? Make sure to specify your null and alternative hypotheses and give a brief conclusion.

b. Conduct a trend test using row scores S1 = 0, S2 = 1, and S3 = 2 and using the two-sided alternative hypothesis. Make sure to specify your null and alternative hypotheses and give a brief conclusion.

Answer 1