Common variants within the interleukin 4 receptor alpha gene (IL4R) are associated with susceptibility to osteoarthritis.
Primary osteoarthritis (OA) is a common late-onset arthritis that demonstrates a complex mode of transmittance with both joint-site and gender-specific heterogeneity. We have previously linkage-mapped an OA susceptibility locus to a 12-cM interval at chromosome 16p12.3-p12.1 in a cohort of 146 affected female sibling-pair families ascertained by total hip replacement (female-THR families), with a maximum multipoint LOD score of 1.7. Despite the low LOD score, we were encouraged to investigate this interval further following the report of a linkage to the same interval in an Icelandic pedigree with an early-onset form of hip OA. Using public databases, we searched the interval for plausible candidates and concluded that the gene encoding the interleukin 4 receptor alpha chain (IL4R) was a particularly strong candidate based on its known role in cartilage homeostasis. We genotyped nine common single nucleotide polymorphisms (SNPs) from within IL4R, including six non-synonymous SNPs, in the 146 probands from our female-THR families (stage 1) and in an independent cohort of 310 female-THR cases (stage 2). We compared allele frequencies with those of 399 age-matched female controls. All individuals were UK Caucasians. The minor alleles of two SNPs demonstrated association in both stages, with the most significant association having a P-value of 0.004 with an odds ratio (OR) of 2.1. These two SNPs defined two associated SNP groups. Inheriting a minor SNP allele from both groups was a particular risk factor (OR=2.4, P=0.0008). Our data suggest that functional variants within the IL4R gene predispose to hip OA in Caucasian females.
Forster
Tracy
T
Institute of Musculoskeletal Sciences, Botnar Research Centre, Nuffield Orthopaedic Centre, University of Oxford, UK.
Chapman
Kay
K
Loughlin
John
J
D000368:Aged; D000483:Alleles; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005787:Gene Frequency; D006622:Hip Prosthesis; D006801:Humans; D015810:Linkage Disequilibrium; D008875:Middle Aged; D010003:Osteoarthritis / Q000235:genetics* / Q000276:immunology* / Q000601:surgery; D020641:Polymorphism, Single Nucleotide; D019948:Receptors, Interleukin-4 / Q000235:genetics*; D044465:White People / Q000235:genetics
D019948:Receptors, Interleukin-4