Table 1.

Additive effects (in SD) of the three SNPs in TMPRSS6, HFE and TF on serum iron, transferrin, transferrin saturation, ferritin, and blood haemoglobin (Hb) and erythrocyte mean cell volume (MCV)

	Adolescent					Adult					Combined
Trait	N	Beta	SE	R2 (%)	P	N	Beta	SE	R2 (%)	P	Beta	SE	P
	rs855791(TMPRSS6)
Iron	2505	−0.183	0.027	2.2	1.6×10−11	2298	−0.191	0.030	1.9	9.9×10−11	−0.187	0.020	1.5×10−20
Transferrin	2513	0.078	0.029	0.4	7.1×10−3	2299	0.069	0.031	0.2	0.023	0.074	0.021	4.9×10−4
Saturation	2503	−0.196	0.027	2.5	9.7×10−13	2294	−0.198	0.029	2.0	1.8×10−11	−0.197	0.020	2.2×10−23
Log10(ferritin)	2512	−0.092	0.028	0.5	8.8×10−4	2301	−0.040	0.030	0.1	0.17	−0.068	0.021	9.3×10−4
Hb	2468	−0.151	0.032	1.1	2.3×10−6	3188	−0.067	0.025	0.2	7.7×10−3	−0.099	0.020	5.3×10−7
MCV	2467	−0.139	0.032	0.9	1.3×10−5	3181	−0.120	0.025	0.7	1.8×10−6	−0.127	0.020	1.1×10−10
	rs1800562 (HFE)
Iron	2502	0.343	0.052	2.2	4.7×10−11	2299	0.315	0.053	1.5	2.5×10−9	0.329	0.037	8.2×10−19
Transferrin	2510	−0.602	0.056	6.0	4.3×10−27	2300	−0.605	0.055	5.4	2.9×10−28	−0.604	0.039	2.2×10−53
Saturation	2500	0.598	0.053	6.6	2.3×10−29	2295	0.523	0.054	4.2	3.0×10−22	0.561	0.038	8.5×10−50
Log10(ferritin)	2509	0.168	0.053	0.5	1.6×10−3	2302	0.103	0.054	0.2	0.06	0.136	0.038	3.4×10−4
Hb	2465	0.236	0.061	0.8	1.2×10−4	3451	0.169	0.051	0.3	9.0×10−4	0.197	0.039	5.1×10−7
MCV	2464	0.148	0.061	0.3	0.015	3442	0.273	0.051	0.8	7.7×10−8	0.222	0.039	1.5×10−8
	rs3811647 (TF)
Iron	2505	0.073	0.029	0.3	0.012	2299	0.042	0.032	0.1	0.18	0.059	0.022	0.006
Transferrin	2513	0.460	0.031	11.2	4.4×10−50	2300	0.371	0.032	6.1	2.1×10−30	0.417	0.022	2.1×10−78
Saturation	2503	−0.089	0.029	0.5	2.4×10−3	2295	−0.093	0.031	0.4	3.1×10−3	−0.091	0.021	1.8×10−5
Log10(ferritin)	2512	−0.053	0.029	0.2	0.07	2302	−0.030	0.032	0.1	0.35	−0.044	0.022	0.04
Hb	2468	−0.019	0.034	0.02	0.58	3470	0.032	0.026	0.04	0.21	0.013	0.021	0.52
MCV	2467	−0.041	0.034	0.1	0.23	3461	−0.042	0.026	0.1	0.10	−0.042	0.021	0.04

Note: The results are from the Australian cohorts, except for Hb and MCV in adults (which are from the Dutch cohort). The results in the adolescent cohort are from the mean of measurements from up to 4 visits. The rs855791 variant was not genotyped in the Dutch panel and so was imputed using PLINK ¹¹ as described previously ¹². Genotypes were imputed with high confidence (information score of 0.97) in 92% of individuals. Minor allele frequencies (MAFs) for rs855791 (T), rs1800562 (A) and rs381164 (A) in the adolescent cohort are 0.42, 0.08 and 0.33, respectively. R² is the proportion of the phenotypic variance explained by each SNP. After correction for multiple testing, there is no significant evidence for heterogeneity between the effect sizes in adolescent and adult data.