Predicted secondary structure of L-subunit IRE and mutations described so far in families with hereditary hyperferritinemia. Town names denote different mutations: Paris,26,27 Verona,27 and Pavia 1 and 2 (present work, family 1 and 2). For each mutation, the observed range of hyperferritinemia and the severity of cataract are reported. Clearly, the highest ferritin levels were found in patients with mutations within the CAGUG sequence of the loop, whereas the lowest ones were those of the family with the double mutation in the lower stem. Cataract was judged severe when there was a marked loss in visual acuity in the first decades (with some individuals requiring surgery), mild when the defect in visual acuity could be corrected with the use of appropriate eyeglasses, and asymptomatic when it did not impair visual acuity. It is apparent that a relationship between the degree of hyperferritinemia and severity of cataract exists within the families described so far. Numbers (+18, +22, +32, +40, +41) indicate the nucleotide position according to Table 2 with position +1 being the start of transcription.