title: An Association Study of Interleukin 18 Receptor Genes (IL18R1 and IL18RAP) in Lumbar Disc Degeneration.
abstract: OBJECTIVE
  To examine association of candidate genetic variants in structural, inflammatory, matrix modifying, vitamin D receptor genes and variants associated with osteoarthritis, with surgical candidates and surgical patients with lumbar disc degeneration (LDD), in light of their previously reported susceptibility for LDD.
  
  
  METHODS
  Genotyping of 146 Norwegian LDD patients and 188 Norwegian controls was performed for 20 single-nucleotide polymorphisms (SNPs) from collagen, aggrecan, interleukin, VDR, MMP3 and COX2 genes and 7 SNPs from osteoarthritic genes.
  
  
  RESULTS
  The neighboring genes IL18R1 and IL18RAP polymorphisms (rs2287037 and rs1420100), showed a statistically non-significant risk for developing LDD (OR 1.36 [95 % CI 0.99 - 1.87]; p=0.06 and OR 1.33 [95 % CI 0.98-1.81]; p=0.07). Homozygosity of these risk alleles was associated with LDD (p=0.023 and p=0.027). The non-risk alleles at these SNPs were situated on a haplotype negatively associated with LDD (p=0.008). Carriage of at least one non-risk allele at both loci also reduces the risk of developing LDD (OR 0.51 [95 % CI 0.33-0.80]; p=0.003).
  
  
  CONCLUSIONS
  Our findings support the polygenic nature of LDD and suggest that variation in interleukin 18 receptor genes could affect the risk of severe LDD and associated low back pain.
authors.affiliation: Department of Orthopaedics, Oslo University Hospital-Rikshospitalet, Oslo, Norway.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Omair
authors.forename: Benedicte Alexandra
authors.initials: BA
authors.lastname: Lie
authors.forename: Olav
authors.initials: O
authors.lastname: Reikeras
authors.forename: Jens Ivar
authors.initials: JI
authors.lastname: Brox