Background: We investigated patients who had unexplained hepatic iron overload and normal transferrin saturation.
Methods: 65 patients with a median liver iron concentration of 65 mumol/g dry weight of liver (normal < 36 mumol/g), hyperferritinaemia (566 micrograms/L; normal < 400 micrograms/L), and normal transferrin saturations (32%) were compared with genetic haemochromatosis (GH) controls including homozygous (matched for sex and serum ferritin concentration) and heterozygous individuals. Relatives of patients who had ratios of liver iron concentration to age greater than 1.9 were also studied.
Findings: The 65 patients were significantly older and had significantly less hepatic iron overload than individuals with genetic haemochromatosis. The frequency of HLA-A3 antigen was significantly lower in these patients than in individuals with homozygous (p < 0.0001) or heterozygous (p < 0.0002) GH. Five HLA-identical siblings of the patients had normal serum ferritin concentrations. Most of the patients (95%) had one or more of the following conditions; obesity, hyperlipidaemia, abnormal glucose metabolism, or hypertension.
Interpretation: We have found a new non-HLA-linked iron-overload syndrome which suggests a link between iron excess and metabolic disorders. The current diagnostic criteria for genetic haemochromatosis should be reviewed.