The estimated prevalence of systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) in women with trisomy X (47,XXX) was respectively ∼2.5 and ∼2.9 times higher than in 46,XX women and ∼25 and ∼41 times higher than in 46,XY men. This according to a study of female patients with SLE and SS, as well as controls. Researchers found:

• 7 of 2,826 patients with SLE also had 47,XXX, a ratio of ∼1 in 404.

• 3 of 1,033 patients with SS also had 47,XXX, a ratio of ∼1 in 344.

• 2 of 7,074 controls had 47,XXX, a ratio of 1 in 3,537.

• No statistically significant increase of 47,XXX was seen in other female-biased diseases, such as primary bilious cirrhosis and rheumatoid arthritis, supporting the idea of multiple pathways to sex bias in autoimmunity.

Citation: Liu K, Kurien BT, Zimmerman SL, et al. X chromosome dose and sex bias in autoimmune diseases: Increased 47,XXX in systemic lupus erythematosus and Sjögren's Syndrome. [Published online ahead of print December 29, 2015]. Arthritis Rheumatol. doi: 10.1002/art.39560.