Table 2. Comparison of GDF-5 genotypes and allele frequencies between KOA patients and controls.

GDF-5: growth/differentiation factor 5; KOA: knee osteoarthritis

GDF-5 genotypes	KOA patients		Controls		Chi-square (χ2)	P-value	Odds ratio (95% confidence interval)
	N	%	N	%
TT	18	30	13	22	3.86	0.049	0.33 (0.12-0.89)
TC	30	50	21	35	5.44	0.019	0.32 (0.13-0.78)
CC	12	20	26	43	Reference
Allele frequencies
T	66	55	47	39	6.037	0.014
C	54	45	73	61