Bone Mineral Density and Trabecular Bone Score in Children, Adolescents and Young Adults with Familial Dysautonomia

Familial dysautonomia (FD) is characterized by skeletal morbidity, including osteoporosis and increased fracture risk. We aimed to assess bone mineral density (BMD) and trabecular bone score (TBS) in individuals with FD, and to explore correlations with disease severity. This retrospective study included all the patients with FD who performed at least one dual-energy X-ray absorptiometry (DXA) scan at our institution during 2015-2023. Demographic and clinical data obtained from medical records included: medical treatment, anthropometric measurements, Functional Severity Scale (FuSS) score, balance assessment, the Brief Ataxia Rating Scale score, ambulation ability, blood test results and fracture history. Forty-one patients (21 males) had at least one DXA scan. The median age at the first scan was 25 years (range 7-47). The mean BMD Z-score was - 1.2 ± 1.5 at the lumbar spine and - 1.3 ± 1.1 at the bilateral proximal femur. The mean TBS Z-score was - 1.8 ± 1.6. The bilateral proximal femur BMD Z-score correlated with better scores of balance (r = 0.612, p = 0.001), ambulation (r = 0.627, p = 0.001) and ataxia (r = - 0.470, p = 0.015). For 67% of the patients, C-terminal telopeptides of type I collagen (CTX) was above the normal range for age. Both CTX and procollagen type I N-terminal propeptide (P1NP) correlated negatively with FuSS (r = - 0.515, p = 0.10 and r = - 0.619, p = 0.042, respectively) and with L_1-4 Z-scores (r = - 0.681, p = 0.03 and r = - 0.700, p = 0.02, respectively). Individuals with FD had low BMD and TBS Z-scores. These parameters were correlated to disease severity, specifically to balance and ambulation. The bone resorption marker was high and negatively correlated with disease severity.