EXT1 and systemic lupus erythematosus: Unlike the patients with primary MN, patients with EXT1/2 positive MN are young with a mean age of 35 years, 81% are females, 71% have signs of autoimmunity such as positive anti-nuclear, anti–double-stranded DNA, anti-SSA/SSB, or anti-ribonucleoprotein antibodies, and a clinical diagnosis of lupus could be posed in 35% of them.