Complete complement deficiency in a large cohort of familial systemic lupus erythematosus. First published online ahead of print 12th November 2009, DOI: 10.1177/0961203309346508. The authors wish to apologize for the misspelling of the authors name, it should read A D'Souza and both AD'Souza and RH Scofield should be affiliated to all three affiliations shown.