TRIM21 and osteoporosis: Notably, we found that Trim21 mRNA levels were increased in patients with osteoporosis (right femur (RF)-BMD T score ≤ −2.5) and osteopenia (RF-BMD T score ≤ −1.0 and > −2.5) compared with those with normal BMDs (T score > −1.0) (Fig. 1a).