Why is Lupus Less Common in Men than Women?

Several recent studies finding answers

New Study Shows Lupus more dependent on genes in men than in women

Men must inherit a greater number of genetic risk factors for lupus to develop the disease compared to women, according to research just published.This higher ‘threshold’ of genetic risk for lupus in men suggests that it is much harder for men to develop the disease and may provide a new explanation as to why the disease is around nine-times less common in men than in women.

An international team of researchers, led by Dr. Amr Sawalha at the University of Oklahoma Health Sciences Center, set out to discover if men and women have different genetic risk factors for lupus. They looked for the presence of known genetic risk factors for lupus in 7,000 lupus patients and controls and found that compared with women, men with lupus had a greater number of predisposing genes on their non-sex or autosomal chromosomes.

The researchers propose that a higher genetic risk threshold in men combined with hormonal and sex chromosome-based genetic differences, account for the disparity in the incidence of lupus between men and women.The findings are published in the November 2011 issue of Annals of the Rheumatic Diseases.

Dr Amr Sawalha is a current recipient of a Lupus Research Institute Novel Research Grant looking into how the proper control of immune system genes may be compromised in lupus.

LRI-funded research on lupus sex bias

Recent work funded by the Lupus Research Institute (LRI)) has provided further insight into male-female disparities in lupus.

Last year, Dr. Betty Tsao of University of California, Los Angeles, identified a genetic factor present on the X sex chromosome associated with lupus in men. Women carry two X chromosomes but men carry only one.

Also funded by LRI, Dr Tyler Curiel of University of Texas is currently investigating whether critical regulatory T cells of the immune system are defective in female but not male mice with lupus.

Dr. Roberto Caricchio, Temple University, Philadelphia is looking at an enzyme, PARP1, in lupus kidney disease in men and whether PARP1-inhibitors have potential as targeted treatment for male lupus.