RNA was extracted from the articular cartilage chondrocytes of 25 individuals who had undergone joint replacement for OA and who were heterozygous for one of the two FRZB SNPs. Allelic output was measured by single base extension in to the SNPs and deviations from the expected 1:1 pattern were assessed using the Mann2013;Whitney U test.
Differential allelic expression was observed in six of the 25 individuals. However, the average fold difference in allelic expression in the six was only 1.19.
The presence of a small degree of differential allelic expression in a low proportion (24 % ) of the individuals studied suggests that polymorphism in FRZB cis-acting regulatory elements can be discounted as a major factor that could influence the development of OA.