Table 1.

Distribution of the collagen gene genotypes, alleles, and carriage rates in persons with and without disc degeneration at the L3/L4 and L4/L5 disc levels

	Dark nucleus pulposus			Disc bulges			Decreased disc height			Summary scorea
	No	One	Two	No	One	Two	No	One	Two	0	1–2	3–4
COL2A1
AA	1	0	0	1	0	0	1	0	0	1	0	0
AG	4	7	4	5	7	3	7	6	2	4	7	4
GG	46	39	23	52	37	19	45	38	25	46	42	20
A allele frequency	0.06	0.08	0.07	0.06	0.09	0.07	0.08	0.07	0.05	0.06	0.08	0.08
A allele carriage	9.8	15.2	14.8	10.3	15.9	13.6	15.1	13.6	7.4	9.8	14.3	16.7
OR (95%CI)b	1.4 (0.5–3.6)			1.4 (0.5–3.7)			0.6 (0.2–1.6)			1.4 (0.5–3.9)
COL11A2
AA	2	0	0	1	1	0	1	1	0	2	0	0
AG	14	18	12	16	16	12	18	14	12	14	19	11
GG	37	29	15	43	27	11	37	39	15	37	31	13
A allele frequency	0.17	0.19	0.22	0.15	0.21	0.26	0.17	0.18	0.23	0.17	0.19	0.23
A allele carriage	30.2	38.3	44.4	28.3	38.6	52.2	33.9	34.1	44.4	30.2	38.0	45.8
OR (95%CI)	1.6 (0.8–3.1)			2.1 (1.0–4.2)			1.3 (0.6–2.5)			1.6 (0.8–3.2)
COL9A3
Carrier of the Trp3c	8	9	6	10	8	5	10	7	6	8	9	6
Non-carrier of the Trp3	47	39	23	53	37	19	48	38	23	47	42	20
Trp3 allele frequency	0.07	0.09	0.12	0.08	0.09	0.13	0.09	0.08	0.12	0.07	0.09	0.13
Trp3 allele carriage	14.5	18.8	20.7	15.9	17.8	20.8	17.2	15.5	20.7	14.5	17.6	23.1
OR (95%CI)	1.4 (0.6–3.3)			1.3 (0.5–3.0)			1.1 (0.5–2.6)			1.5 (0.7–3.5)

Disc degeneration is assessed as number of the disc with degenerative signs

^aJoint occurrence of the dark nucleus pulposus, disc bulges and decreased disc height

^bProportional odds model. Odds ratios (OR) and their 95% confidence intervals (95% CI) adjusted for occupation and BMI at the age of 40–45 years

^cOnly one individual was homozygous for the Trp3 allele, this person had all degenerative changes at both disc levels