Table 4. Genetic variants identified as potential modifiers of hemochromatosis type-1 phenotype.

Gene	Function	SNP	Type of study	Patients (N; origin)	Effect	Reference
CYBRD1	Iron absorption	rs884409	Association iron genes	98; North Europe	Ferritin	Constantine et al. (111)
CYBRD1	Iron absorption	rs3806562	Association iron genes	294; Italian	TSAT	Pelucchi et al. (108)
BMP2	Hepcidin synthesis	rs235657	Association iron genes	592; French	Ferritin	Milet et al. (112)
BMP2	Hepcidin synthesis	rs235657	Association iron genes	450; French	Iron removed (IR)	Milet et al. (112)
TF	Iron transport	rs3811647	GWAS	474+748; French + Italian	Transferrin serum iron	De Tayrac et al. (105)
GNPAT*	Lipid synthesis	rs11558492	Exome sequence	35 extreme phenotypes; USA	Iron overload	McLaren et al. (109)
PNPLA3	Liver fat	rs738409	Association	174; Italian	Liver steatosis, fibrosis	Valenti et al. (77)
PCSK7	TFR1 shedding, TGF-β synthesis	rs236918	GWAS association	148+611; North Europe 298; Italian	Liver fibrosis, liver fibrosis	Stickel et al. (78), Pelucchi et al. (79)

*, after the first report by McLaren et al. (109), several other studies were published some confirming (113) other not confirming the role of the polymorphism as modifier of HFE-related hemochromatosis (114-116).