Table 4. Frequency of the rs1061170 CFH Y402H risk allele ‘C’ by category of AMD.

AMD category	AREDS cohort			Familial AMD cohort			Case control cohort
	Number of individuals	‘C’ allele frequency	P value	Number of individuals	‘C’ allele frequency	P value	Number of individuals	‘C’ allele frequency	P value
1	306	0.36		97	0.47		211	0.36
2	502	0.38	0.46	55	0.49	0.84
3	526	0.48	<10−5	95	0.63	0.002
4	578	0.61	<10−22	124	0.63	0.001	183	0.59	<10−10

P-values calculated for allelic test of association for differences in AMD grade (categories 2, 3 and 4) from category 1 (no AMD)