title: A CHI3L1 gene polymorphism is associated with serum levels of YKL-40, a novel sarcoidosis marker.
abstract: BACKGROUND
  YKL-40, a chitinase-like cartilage glycoprotein, has recently shown its potential as a marker for sarcoidosis.
  
  
  METHODS
  This study aimed to assess whether YKL-40 at presentation may predict the course of sarcoidosis over a 4-year follow-up period and to investigate whether polymorphisms in the chitinase 3-like 1 (CHI3L1) gene might influence serum YKL-40 levels in sarcoidosis patients (n=63) and controls (n=333).
  
  
  RESULTS
  Patients had significantly higher (mean, 95% CI) serum YKL-40 levels (181.3 ng/ml, 50.7-648.1) compared to controls (36.6 ng/ml, p<0.0001. Serum YKL-40 was elevated in 79% of the patients and was inversely correlated with DLco at presentation (r(2)=-0.27, p=0.03), but not after 2-4 years of follow-up (r(2)=-0.16, p=0.27). Serum YKL-40 levels in controls were dependent on the CHI3L1 -329 G/A polymorphism (mean, 95% CI): GG (n=213) 48.3 ng/ml, 41.7-56.0; GA (n=101) 31.2 ng/ml, 26.6-36.3; AA (n=17) 17.8 ng/ml, 13.6-23.4, p<0.0001. In patients, this effect was not observed.
  
  
  CONCLUSIONS
  YKL-40 may be used as a sarcoidosis disease marker, but it is unsuitable as a marker to predict the course of the disease. The CHI3L1 -329 G/A polymorphism contributes to inter-individual variations of YKL-40 levels, but does not influence sarcoidosis disease susceptibility or severity.
authors.affiliation: Department of Pulmonology, Heart Lung Centre Utrecht, St. Antonius Hospital, Nieuwegein, The Netherlands.
authors.forename: Adrian
authors.initials: A
authors.lastname: Kruit
authors.forename: Jan C
authors.initials: JC
authors.lastname: Grutters
authors.forename: Henk J T
authors.initials: HJ
authors.lastname: Ruven
authors.forename: Coline C M
authors.initials: CC
authors.lastname: van Moorsel
authors.forename: Jules M M
authors.initials: JM
authors.lastname: van den Bosch
mesh_terms: D054392:Adipokines; D000328:Adult; D000367:Age Factors; D015415:Biomarkers / Q000097:blood; D000071451:Chitinase-3-Like Protein 1; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D006023:Glycoproteins / Q000097:blood* / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D037102:Lectins; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D017565:Sarcoidosis, Pulmonary / Q000097:blood / Q000235:genetics*
chemical_list: D054392:Adipokines; D015415:Biomarkers; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D037102:Lectins