The identification of a gene associated with immunoglobulin A nephropathy (IgAN) has, for the first time, raised the possibility that the kidney disease may be an inherited disorder. It is hoped that the study, reported in November
Dr Richard P Lifton and colleagues from the Howard Hughes Medical Institute analysed 30 families in Italy and the US. They found a strong association between IgAN and a gene on chromosome 6 in 60% of the families. "Our analyses indicate an odds ratio of 400,000 to one in favour of a linkage of this locus with the disease in the affected families," Dr Lifton said. He believes that the gene might provide clues to whether environmental influences trigger the disease, which would explain why the disease follows an upper respiratory infection or cold. "It would also explain why not everyone who inherits the gene ends up getting the disease," he said. A possible explanation could be that the culprit gene influences IgA metabolism, resulting in the IgA deposits characteristic of the disease that cause the kidneys to become scarred.
The researchers are now trying to identify the gene involved, and are recruiting patients from different ethnic groups in order to determine whether the wide variation in disease occurrence is due to different frequencies of the mutant gene in different populations.