Natural history of juvenile haemochromatosis.

Juvenile haemochromatosis or haemochromatosis type 2 is a rare autosomal recessive disorder which causes iron overload at a young age, affects both sexes equally and is characterized by a prevalence of hypogonadism and cardiopathy. Patients with haemochromatosis type 2 have been reported in different ethnic groups. Linkage to chromosome 1q has been established recently, but the gene remains unknown. We report the analysis of the phenotype of 29 patients from 20 families of different ethnic origin with a juvenile 1q-associated disease. We also compared the clinical expression of 26 juvenile haemochromatosis patients with that of 93 C282Y homozygous males and of 11 subjects with haemochromatosis type 3. Patients with haemochromatosis type 2 were statistically younger at presentation and had a more severe iron burden than C282Y homozygotes and haemochromatosis type 3 patients. They were more frequently affected by cardiopathy, hypogonadism and reduced glucose tolerance. In contrast cirrhosis was not statistically different among the three groups. These data suggest that the rapid iron accumulation in haemochromatosis type 2 causes preferential tissue damage. Our results clarify the natural history of the disease and are compatible with the hypothesis that the HFE2 gene has greater influence on iron absorption than other haemochromatosis-associated genes.