Aggrecan gene variant may modulate RA risk | Arthritis Information

 A polymorphism in the gene encoding aggrecan (ACAN) is associated with rheumatoid arthritis (RA), a Brazilian case–control study has found.

Aggrecan is a major proteoglycan found in hyaline cartilage, where it creates osmotic swelling pressure and draws water into the tissue.

In this study, Thais de Souza (Universidade Luterana do Brasil) and colleagues hypothesized that a variable number of tandem repeats (VNTR) polymorphism in the ACAN would be associated with RA.

“The length of the core protein varies directly with repeat numbers, and this length variation may lead to changes in cartilage function,” they write in the Journal of Rheumatology.

De Souza et al recruited 170 patients with RA and 148 healthy controls and genotyped them for the ACAN VNTR polymorphism. All participants were Brazilians of European descent.

Their study revealed that alleles of shorter length were significantly more common in RA patients than in controls.

They also found that the allele score, defined as the sum of the lengths of the 2 ACAN alleles for each participant, was lower in RA patients than in controls (52.7