title: Protein Z deficiency in antiphospholipid-negative Sneddon's syndrome.
abstract: BACKGROUND
  Sneddon's syndrome is characterized by the association of ischemic cerebrovascular events and widespread livedo racemosa. The pathophysiology of Sneddon's syndrome remains elusive, but various prothrombotic abnormalities have been previously reported in this setting. Low levels of protein Z, a downregulator of coagulation, have been recently linked to an increased risk of arterial thrombosis. The purpose of this study was to investigate the levels of protein Z in a series of Sneddon's syndrome patients without circulating antiphospholipid antibodies in comparison with an age- and sex-matched control population.
  
  
  METHODS
  Twenty-six patients and 78 healthy controls had determination of their protein Z blood levels by an enzyme-linked immunoassay test. Patients' thrombotic and vascular risk factors, including tobacco smoking, arterial hypertension, oral contraceptive agents, dyslipidemia, factor V Leiden, and factor II mutation were recorded.
  
  
  RESULTS
  Protein Z plasma levels were significantly lower in patients (mean 1.47 mg/L) than in controls (mean 1.93 mg/L) (P=0.02). Prevalence of protein Z deficiency (level <1 mg/L) was significantly higher (P=0.001) among patients (31%) than among controls (3.8%). Factor V Leiden and heavy smoking were observed in 4 and 7 patients, respectively.
  
  
  CONCLUSIONS
  Sneddon's syndrome could be viewed as the peculiar clinical expression of various and sometimes associated coagulation abnormalities. Low levels of protein Z may account, at least partly, for the thrombotic events observed in Sneddon's syndrome and shed a new light on its pathophysiology. Clinical implications for protein Z deficiency in this setting deserve further investigations.
authors.affiliation: Internal Medicine-Dermatology Department, Pitié-Salpêtrière Hospital, Paris, France.
authors.forename: Nakhlé
authors.initials: N
authors.lastname: Ayoub
authors.forename: Gaetan
authors.initials: G
authors.lastname: Esposito
authors.forename: Stéphane
authors.initials: S
authors.lastname: Barete
authors.forename: Claudine
authors.initials: C
authors.lastname: Soria
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Piette
authors.forename: Camille
authors.initials: C
authors.lastname: Francès
mesh_terms: D000328:Adult; D017152:Antibodies, Antiphospholipid / Q000097:blood; D001798:Blood Proteins / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018860:Sneddon Syndrome / Q000097:blood* / Q000175:diagnosis
chemical_list: D017152:Antibodies, Antiphospholipid; D001798:Blood Proteins; C026080:plasma protein Z