Genetics and Bone Mineral Density Predict the Fractures in Adults With Osteogenesis Imperfecta: A Prospective Study.

CONTEXT: Osteogenesis imperfecta (OI) is a rare genetic bone disorder characterized by recurrent fractures. In adults, the value of bone mineral density (BMD) in fracture risk is unknown.

OBJECTIVE

We prospectively investigated changes in BMD over time and analyzed the determinants of fracture in OI.

METHODS

Among 106 individuals with grade 1 and 4 OI in the Reference Centre of Rare Bone Diseases in Paris, we included those with BMD measurements at 1 or more skeletal sites (hip, lumbar spine, radius) from 2000 to 2022.

RESULTS

For 71 individuals with reliable measurements (44 women, 8 postmenopausal; mean age 41.4 ± 13.7 years), baseline BMD was low at the lumbar spine only (mean Z-score -2.3 ± 1.5), affecting mainly men (mean Z-score -3 ± 1.6). Longitudinal changes were assessed for a median follow-up of 5.1 years (interquartile range 3.2-8.8). On adjustment for age, sex, and body mass index, BMD did not significantly change at any site. Logistic regression analysis revealed a high probability of fracture with baseline BMD Z-score <-2 SD vs ≥-2 SD [odds ratio 4.38, 95% confidence interval (CI) 1.10-21.75, P = .048] and harboring splicing, stop codon, and frameshift variants of COL1 gene (odds ratio 29.8, 95% CI 2.56-1503, P = .024).

CONCLUSION

Our OI cohort showed low BMD at the lumbar spine but no significant change at any site after a median of 5.0 years of follow-up. The probability of fracture was associated with baseline BMD Z-score <-2 SD vs ≥-2 SD and harboring COL1 splicing, stop codon, and frameshift variants.