A DQA1 allele is strongly associated with idiopathic membranous nephropathy.

The high molecular weight genomic DNA from 31 patients with idiopathic membranous nephropathy (IMN) has been digested with a restriction endonuclease Taq I, electrophoresed, blotted and hybridised with probes to the HLA-DRB, -DQA, -DQB, -DPA and -DPB genes. The restriction endonuclease Msp I was also used with the HLA-DPA and -DPB probes. The resulting restriction fragment length polymorphism (RFLP) has been analysed and compared with 55 controls treated in the same way. There was a significant increase in the DRB restriction fragments associated with HLA-DR3 (Fisher's p = 0.011), in particular with a sub-division of DR3 (Fisher's p = 0.0038). These results confirm at the DNA level serological correlations observed for IMN. A 4.5 Kb DQA RFLP was significantly raised in IMN patients (Fisher's p = 0.002) and is proposed as a major disease susceptibility factor.