title: ACE I/D-corrected Z-scores to identify normal and elevated ACE activity in sarcoidosis.
abstract: BACKGROUND
  The value of elevated serum angiotensin-converting enzyme (ACE) activity in the diagnosis and follow-up in sarcoidosis is a matter of ongoing debate. This may be at least related to the insertion (I)/deletion (D) polymorphism in the ACE gene (ACE I/D). ACE activity is influenced by the ACE I/D polymorphism. As a consequence, the use of one reference interval instead of three genotype-specific reference intervals for ACE activity may lead to a less precise interpretation of ACE activity.
  
  
  METHODS
  In order to assess whether determination of ACE activity indeed requires the ACE I/D genotype to be taken into account, we established ACE I/D-corrected reference intervals in healthy, Caucasian volunteers (n=200). In addition, ACE activities in ACE I/D genotyped patients suspected of or having sarcoidosis (n=129) were expressed as the Z-score related to ACE I/D-corrected reference intervals.
  
  
  RESULTS
  Comparison of the Z-score with ACE activity in which ACE I/D is ignored rendered 8.5% misclassification of 'elevated' versus 'normal' ACE or vice versa.
  
  
  CONCLUSIONS
  Our data demonstrate a convenient way to circumvent the use of three reference intervals by introducing a Z-score for ACE activity. It also illustrates the need to re-investigating the possible clinical value of serum ACE activity in sarcoidosis by considering ACE I/D.
authors.affiliation: Heart Lung Centre Utrecht, St. Antonius Hospital, Department of Pulmonology, Koekoekslaan 1, 3435 CM, Nieuwegein, The Netherlands.
authors.forename: Adrian
authors.initials: A
authors.lastname: Kruit
authors.forename: Jan C
authors.initials: JC
authors.lastname: Grutters
authors.forename: Wim B M
authors.initials: WB
authors.lastname: Gerritsen
authors.forename: Snjezana
authors.initials: S
authors.lastname: Kos
authors.forename: Will K W H
authors.initials: WK
authors.lastname: Wodzig
authors.forename: Jules M M
authors.initials: JM
authors.lastname: van den Bosch
authors.forename: Henk J T
authors.initials: HJ
authors.lastname: Ruven
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D005260:Female; D017353:Gene Deletion; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D007703:Peptidyl-Dipeptidase A / Q000097:blood / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D012507:Sarcoidosis / Q000201:enzymology* / Q000235:genetics
chemical_list: D007703:Peptidyl-Dipeptidase A