Exon 2 was replaced with a modified exon 2 in which a C to G point mutation results in the amino acid substitution of aspartic acid for histidine at position 67 (p.H67D). The mutation recapitulates the human mutation, p.H63D, observed in many patients with hereditary hemochromatosis (HH). Cre-mediated recombination removed the loxP site flanked neomycin resistance cassette in intron 2. (J:201948)