HFE-Related Hemochromatosis: The Haptoglobin 2-2 Type Has a Significant but Limited Influence on Phenotypic Expression of the Predominant p.C282Y Homozygous Genotype

Table 3

(a) Regression coefficients (β) and 95% confidence intervals (CIs) for variables influencing serum ferritin (𝝁g/L; log₁₀-transformed) and iron removed by phlebotomy (g; log₁₀-transformed) in p.C282Y homozygous males patients.

Variable	Serum ferritin^1		Iron removed^2
	10^β (95% CI)	P value	10^β (95% CI)	P value
Age at diagnosis^3
Quartile 2	1.30 (0.99, 1.71)	0.0603	1.29 (0.99, 1.66)	0.0567
Quartile 3	1.87 (1.39, 2.51)	< 0.0001	1.39 (1.05, 1.68)	0.0204
Quartile 4	1.59 (1.19, 2.13)	0.0019	1.50 (1.15, 1.96)	0.0032
Alcohol consumption^4	1.59 (1.18, 2.16)	0.0027	1.50 (1.11, 2.04)	0.0096
Hp group^5	1.40 (1.13, 1.74)	0.0026	1.38 (1.12, 1.69)	0.0022

(b) Regression coefficients (β) and 95% confidence intervals (CIs) for variables influencing serum ferritin (𝝁g/L; log₁₀-transformed) and iron removed by phlebotomy (g; log₁₀-transformed) in p.C282Y homozygous females patients.

Variable	Serum ferritin^1		Iron removed^2
	10^β (95% CI)	P value	10^β (95% CI)	P value
Age at diagnosis^3
Quartile 2	1.26 (0.83, 1.89)	0.2723	1.31 (0.90, 1.91)	0.1574
Quartile 3	1.85 (1.23, 2.78)	0.0033	1.58 (1.09, 2.29)	0.0154
Quartile 4	2.38 (1.58, 3.59)	<0.0001	1.87 (1.29, 2.71)	0.0012
Alcohol consumption^4	1.37 (0.37, 5.01)	0.6351	1.65 (0.53, 5.15)	0.3892
Hp group^5	1.20 (0.89, 1.61)	0.2383	1.17 (0.90, 1.53)	0.2457

¹N = 195. Adjusted r² = 16.2%.
² N = 178. Adjusted r² = 13.5%.
³ Quartile 1 was used as the reference category.
⁴ Daily alcohol intake < 60 g was used as the reference category.
⁵ Hp1-1 and Hp2-1 genotypes were grouped and used as the reference category.