Relationship between cytosine-adenine repeat polymorphism of ADAMTS9 gene and clinical and radiologic severity of knee osteoarthritis

Objective: The aim of this study is to determine the role of cytosine-adenine (CA) micro-satellite repeat sequence of ADAMTS9 gene on the development and progression of osteoarthritis (OA). Methods: A total of 110 participants, including those with primary knee OA and healthy controls were enrolled in the study. Patients were stratified into two groups using the Kellgren–Lawrence staging (K–L staging) as group 1 for controls and mild OA and group 2 for moderate and severe OA. Genetic analyses were performed to determine the CA repeat length in ADAMTS9 gene. Results: Twenty CA repeats were found to be statistically significant for differentiating groups 1 and 2 (P = 0.020). Age was the most significant risk factor involved, followed by ≥ 20 CA repeats and body mass index (P < 0.05). CA repeat length of ≥ 20 showed a 6.1-fold increase in probability for having OA at stage 3 or 4 compared to those of CA repeat length of < 20 (P = 0.004). In conclusion, the CA repeat length of ≥ 20 has a six-fold increase in probability for having severe OA. Conclusion: ADAMTS9 gene CA repeat polymorphism may be used to determine the prognosis for OA radiologic progression. Being the first in the literature reporting the CA repeat in the promotor region of ADAMTS9 gene in patients with OA, our study could be highlighted further in future research with larger sample size.