An Association Study of Interleukin 18 Receptor Genes (IL18R1 and IL18RAP) in Lumbar Disc Degeneration
Ahmad Omair*, 1, Benedicte Alexandra Lie2, Olav Reikeras1, Jens Ivar Brox1
1 Department of Orthopaedics, Oslo University Hospital-Rikshospitalet, Oslo, Norway
2 Department of Immunology, Oslo University Hospital-Rikshospitalet, Oslo, Norway
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.
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.
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).
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.
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* Address correspondence to this author at the Department of Orthopaedics, Oslo University Hospital-Rikshospitalet, Sognsvannsveien 20, 0027 Oslo, Norway; Tel: +47-93687989, +47-23076053; Fax: +47-23076010; E-mail: firstname.lastname@example.org