title: Genetic variation in KLK2 and KLK3 is associated with concentrations of hK2 and PSA in serum and seminal plasma in young men.
abstract: BACKGROUND
  Genetic variants in KLK2 and KLK3 have been associated with increased serum concentrations of their encoded proteins, human kallikrein-related peptidase 2 (hK2) and prostate-specific antigen (PSA), and with prostate cancer in older men. Low PSA concentrations in seminal plasma (SP) have been associated with low sperm motility. To evaluate whether KLK2 and KLK3 genetic variants affect physiological prostatic secretion, we studied the association of SNPs with hK2 and PSA concentrations in SP and serum of young, healthy men.
  
  
  METHODS
  Leukocyte DNA was extracted from 303 male military conscripts (median age 18.1 years). Nine SNPs across KLK2-KLK3 were genotyped. We measured PSA and hK2 in SP and serum using immunofluorometric assays. The association of genotype frequencies with hK2 and PSA concentrations was tested with the Kruskal-Wallis test.
  
  
  RESULTS
  Four KLK2 SNPs (rs198972, rs198977, rs198978, and rs80050017) were strongly associated with hK2 concentrations in SP and serum, with individuals homozygous for the major alleles having 3- to 7-fold higher concentrations than the intermediate concentrations found in other homozygotes and heterozygotes (all P < 0.001). Three of these SNPs were significantly associated with percentage of free PSA (%fPSA) in serum (all P < 0.007). Three KLK3 SNPs showed associations with PSA in SP, and the rs1058205 SNP was associated with total PSA in serum (P = 0.001) and %fPSA (P = 0.015).
  
  
  CONCLUSIONS
  Associations observed in young, healthy men between the SP and serum concentrations of hK2 and PSA and several genetic variants in KLK2 and KLK3 could be useful to refine models of PSA cutoff values in prostate cancer testing.
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Chemistry, and.
authors.forename: Charlotta
authors.initials: C
authors.lastname: Sävblom
authors.forename: Christer
authors.initials: C
authors.lastname: Halldén
authors.forename: Angel M
authors.initials: AM
authors.lastname: Cronin
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Säll
authors.forename: Caroline
authors.initials: C
authors.lastname: Savage
authors.forename: Emily A
authors.initials: EA
authors.lastname: Vertosick
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Klein
authors.forename: Aleksander
authors.initials: A
authors.lastname: Giwercman
authors.forename: Hans
authors.initials: H
authors.lastname: Lilja
mesh_terms: D000293:Adolescent; D056726:Genetic Association Studies; D006801:Humans; D007610:Kallikreins / Q000032:analysis / Q000235:genetics*; D008297:Male; D020641:Polymorphism, Single Nucleotide; D017430:Prostate-Specific Antigen / Q000032:analysis / Q000235:genetics*; D012016:Reference Values; D012661:Semen / Q000201:enzymology*; D044967:Serum; D020840:Tissue Kallikreins / Q000032:analysis / Q000235:genetics; D055815:Young Adult
chemical_list: C549870:KLK3 protein, human; D007610:Kallikreins; D020840:Tissue Kallikreins; D017430:Prostate-Specific Antigen