Multiallelic polymorphism of the cartilage collagen gene: no association with osteoarthrosis

To determine whether any of the type II collagen alleles are associated with generalised osteoarthrosis or osteoarthrosis of the finger joints in the genetically isolated Finnish population.

Two patient cohorts with evidence for only primary osteoarthrosis and a cohort of healthy control subjects were selected from the Helsinki University Central Hospital and the Rheumatism Foundation Hospital in Finland. Forty one patients with primary generalised osteoarthrosis, 49 patients with osteoarthrosis of the finger joints, and 48 control subjects were included. Two markers of the type II collagen gene, a PvuII polymorphism and a VNTR polymorphism, were analysed from each subject.

Four different alleles of the VNTR marker were observed and the relative risks associated with the different VNTR alleles varied between 0.39 and 1.24 among the patients with generalised osteoarthrosis and between 0.67 and 2.33 among the patients with osteoarthrosis of the finger joints. The PvuII polymorphism detected two different alleles and the associated relative risks were 0.82 and 1.82 for the patients with generalised osteoarthrosis, and 1.04 and 0.96 for the patients with osteoarthrosis of the finger joints.

A major predisposing allele of the type II collagen gene as the causative factor for osteoarthrosis could be excluded in this population. A spectrum of mutations associated with different alleles of this gene could not be excluded, however. Further, these two forms of cartilage disease can be caused by gene defects with reduced penetrance and the effect of such an allele is easily masked under the high frequency of normal alleles.