Three siblings with systemic lupus erythematosus.

We present the cases of three siblings with systemic lupus erythematosus (SLE). The diagnosis was made when the sisters were of age 21, 25 and 28 years. They shared some clinical features, including typical facial rash, photosensitivity and Raynaud's phenomenon, and tested positive for antinuclear antibodies. However, their symptoms and clinical courses varied. Human leukocyte antigen (HLA) typing revealed that DR4 and A2 were present in all three sisters, while HLA type A11, B35 and B54 were each found in two of the three sisters. The two elder sisters developed lupus glomerulonephritis 8 and 11 years after the onset of SLE. It is suggested that there are genes responsible for the onset of the disease and also unknown regulatory genes other than HLA result in different phenotypes.