Table 3.

Former classification of HC

Classification	Gene involved and location	Inheritance	TSAT	Other clinical features
Type 1	HFE; chr. 6	AR	Increased	Adult-onset; more severe in males; highly variable clinical expression, with predominant liver damage and arthritis
Type 2A	HJV (hemojuvelin); chr. 1	AR	Increased	Earlier onset (eg, <30 y old); similar severity in both sexes; prevalent cardiac and endocrine involvement
Type 2B	HAMP (hepcidin); chr. 19	AR	Increased	Earlier onset (eg, <30 y old); similar severity in both sexes; prevalent cardiac and endocrine involvement
Type 3	TFR2 (transferrin receptor 2); chr. 7	AR	Increased	Very rare (look for parental consanguinity); clinically similar to type 1, with an earlier onset
Type 4A	SLC40A1 (ferroportin); chr. 2	AD	Low-normal	Adult-onset; IO in the spleen; mild anemia; possible low tolerance to venesection
Type 4B	SLC40A1 (ferroportin); chr. 2	AD	Increased	Very rare; in general, clinically similar to type 1, but more severe/early onset forms are reported

AD, autosomal dominant; AR, autosomal recessive; chr., chromosome.