Systemic lupus erythematosus
The rate of SLE varies between countries, ethnicity, and sex, and changes over time. In the United States, one estimate of the rate of SLE is 53 per 100,000; other estimates range from 322,000 to over 1 million. In Northern Europe the rate is about 40 per 100,000 people. SLE occurs more frequently and with greater severity among those of non-European descent. That rate has been found to be as high as 159 per 100,000 among those of Afro-Caribbean descent. Childhood-onset systemic lupus erythematosus generally presents between the ages of 3 and 15 and is four times more common in girls.
Systemic lupus erythematosus
The discovery of the LE cell led to further research and this resulted in more definitive tests for lupus. Building on the knowledge that those with SLE had auto-antibodies that would attach themselves to the nuclei of normal cells, causing the immune system to send white blood cells to fight off these "invaders", a test was developed to look for the anti-nuclear antibody (ANA) rather than the LE cell specifically. This ANA test was easier to perform and led not only to a definitive diagnosis of lupus but also many other related diseases. This discovery led to the understanding of what are now known as autoimmune diseases.