Increased frequency of HLA-A3 in subjects with sporadic porphyria cutanea tarda.

The HLA-A3 alloantigen, usually associated with the hemochromatosis gene, was detected in 12 of 18 patients (67%) with sporadic porphyria cutanea tarda but in only 23 per cent of 328 normal subjects (p = 0.0006). This difference remained significant after correcting for the number of HLA-A locus antigens tested (p = 0.025). These results suggest that an HLA-linked hemochromatosis allele is present and may account for the iron abnormalities in many patients with sporadic porphyria cutanea tarda.