Evaluation of Fat Distribution by Dual‐Energy X‐Ray Absorptiometry in Patients With Familial Partial Lipodystrophy

ABSTRACT Aims We evaluated orientation‐dependent differences in regional fat‐distribution measures obtained by anteroposterior (AP) and lateral dual‐energy X‐ray absorptiometry (DXA), focusing primarily on comparisons between LMNA ‐associated and non‐ LMNA familial partial lipodystrophy (FPLD) and, secondarily, on distinguishing genetically confirmed FPLD from a matched FPLD‐excluded comparison group. Materials and Methods This retrospective cross‐sectional study included 20 adults with genetically confirmed FPLD (15 LMNA ‐associated, 5 non‐ LMNA ) and 20 frequency‐matched individuals in whom FPLD was clinically suspected but subsequently excluded. All underwent paired AP and lateral whole‐body DXA. Trunk‐to‐leg fat mass ratio (FMR) was the principal parameter. Paired orientation effects, age‐ and sex‐adjusted analyses, false‐discovery‐rate correction and receiver operating characteristic (ROC) analyses were performed. Results The AP‐to‐lateral change in trunk‐to‐leg FMR differed between LMNA ‐associated and non‐ LMNA FPLD (−0.09 ± 0.26 vs. 0.29 ± 0.10; between‐group difference 0.381, 95% CI: 0.211–0.552; adjusted p = 0.026; q = 0.003). Lateral FMR showed a higher exploratory AUC for distinguishing the genetic subgroups, but the five‐person non‐ LMNA subgroup precluded conclusions about diagnostic performance. For FPLD versus the matched FPLD‐excluded comparison group, AP‐derived leg fat mass (FM)/BMI remained strongly discriminatory (AUC 0.953), without improvement with lateral acquisition. Conclusions Orientation‐dependent changes in trunk‐to‐leg FMR differed between LMNA ‐associated and non‐ LMNA FPLD, whereas AP‐derived peripheral‐fat measures showed the highest discrimination between FPLD and the matched FPLD‐excluded comparison group. Lateral DXA may therefore provide complementary information on regional fat distribution; although these exploratory findings do not establish a diagnostic advantage over AP imaging. Its clinical value and reproducibility require validation in larger cohorts.