Objective: To determine whether the recently described hand osteoarthritis (HOA)-associated T303M mutation in the gene for matrilin-3 (MATN3) is associated with specific radiological changes on hand radiographs. Method: Standard hand radiographs from 26 HOA patients carrying the T303M missense mutation in the MATN3 gene (T303M patients) were compared with those from 52 HOA controls matched for sex, age, and clinical disease severity. Two blinded readers scored the radiographs, using the Verbruggen-Veys anatomical scoring system for the interphalangeal and metacarpophalangeal joints and the OARSI atlas scoring system for the first carpometacarpal (CMC1) joints. A scoring system based on the latter was used for the scaphoid-trapezoid- trapezoideum (STT) joints. Results: No particular distinguishing features were found in the T303M patients and the prevalence of erosive and cystic changes was similar to the control group. As a group, however, the T 303M patients had more severe thumb-base affection, particularly in the STT joint. Thus, definite radiological OA in both CMC1 and STT joints and higher STT scores compared with CMC1 were significantly more common in patients carrying the T303M mutation. Radiological scores for joint-space narrowing (CMC1 and STT) and osteophytes (STT) were also significantly higher in the T303M patients. Conclusion: Patients carrying the T 303M mutation in the gene for matrilin-3 express a form of HOA that is radiologically indistinguishable from idiopathic HOA in individual patients but they have more severe thumb-base involvement, particularly in the STT joint. This is the first described genetic mutation that is associated with a common form of osteoarthritis.
We thank radiologist Jörgen Albrechtsen for his help as a substitute reader and secretary Arndis Magnusdottir for her invaluable help. The study was funded by the Icelandic Osteoarthritis Research Fund.