title: The combination of complement deficiency and cigarette smoking as risk factor for cutaneous lupus erythematosus in men; a focus on combined C2/C4 deficiency.
abstract: BACKGROUND
  Although deficiencies in the early components of the complement system were among the first identified genetic risk factors for systemic lupus erythematosus (SLE), only a few studies addressed their significance in patients with cutaneous LE (CLE). Among environmental factors, it was postulated that cigarette smoking might intervene in the pathogenesis of LE.
  
  
  OBJECTIVE
  To describe the clinical and biological features of patients with CLE and a complement deficiency. A secondary objective was to assess cigarette smoking in patients with CLE.
  
  
  METHODS
  A retrospective study including all patients diagnosed as having LE between 1995 and 2003 in the Dermatology Department of Strasbourg University Hospital. Patient charts were reviewed and those patients in whom a C4 and/or C2 deficiency was diagnosed were included. Two patients with a combined C2/C4 deficiency were analysed in detail.
  
  
  RESULTS
  There were 48 females and 37 males (F/M ratio = 1.3), with a mean age of 41 years at diagnosis; 73% of the patients had chronic LE and 27% subacute CLE. Among 32 screened patients, 24 patients with a mean age of 36 years had a complement deficiency; 17 had a C4A deficiency, five a C4B deficiency and two a combined C4A/C2 deficiency. A high proportion (58%) of these patients was male; 82% of the patients were smokers. This was especially true in males: 94% were smokers compared with 69% of females.
  
  
  CONCLUSIONS
  Partial deficiency of C4, C2 or C4 and C2 is a common finding in patients with CLE. Most male patients with CLE are smokers. It is thus suggested that the combination of cigarette smoking and complement deficiency could be a risk factor for LE in men.
authors.affiliation: Clinique Dermatologique and Laboratoire d'Immunologie, Hôpitaux Universitaires de Strasbourg, France.
authors.forename: P
authors.initials: P
authors.lastname: Boeckler
authors.forename: M
authors.initials: M
authors.lastname: Milea
authors.forename: A
authors.initials: A
authors.lastname: Meyer
authors.forename: B
authors.initials: B
authors.lastname: Uring-Lambert
authors.forename: E
authors.initials: E
authors.lastname: Heid
authors.forename: G
authors.initials: G
authors.lastname: Hauptmann
authors.forename: B
authors.initials: B
authors.lastname: Cribier
authors.forename: D
authors.initials: D
authors.lastname: Lipsker
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003175:Complement C2 / Q000172:deficiency*; D003181:Complement C4 / Q000172:deficiency*; D005260:Female; D006801:Humans; D008178:Lupus Erythematosus, Cutaneous / Q000209:etiology* / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*
chemical_list: D003175:Complement C2; D003181:Complement C4