Bone Abstracts

Objectives: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autosomal-recessive disorder caused by mutations in the autoimmune regulator gene resulting in insufficient suppression of autoimmunity. The impact of immunological abnormalities and the resulting endocrinopathies on bone health is largely unknown. We performed a comprehensive evaluation of skeletal parameters in a large cohort of adult patients with APECED.

Methods: All Finnish patients with APECED were invited to the study. Age- and gender-matched control subjects were selected through population register. Spinal radiographs were assessed for vertebral fractures. Volumetric bone mineral density (vBMD) and geometry in the total, trabecular and cortical bone compartments were measured with peripheral quantitative computed tomography (pQCT, XCT-2000) from the radius and tibia.

Results: Altogether 38 patients (22 females; median age 44.0 years, range 19.3–70.1 years) were examined. The patients were shorter (median height SDS (range), −1.3 (−2.9 –+1.4) vs −0.2 (−2.4±2.1), P<0.001)) and had lower BMI (22.3 (15.0–40.7) vs 25.2 (18.8–43.9) kg/m², P=0.001) than the controls. Hypoparathyroidism (median age 6.5 years) and adrenocortical insufficiency (median age 11.0 years) had manifested in >80% of the patients. Ovarian insufficiency had been diagnosed between 12.6 to 36.5 years in 77% of females. Altogether 22 patients (58%) had a positive fracture history (1–5 fractures; median 1 fracture) and seven of them had experienced low energy fractures. Patients had on average experienced more fractures (1.2 per person) than the controls (0.7 per person, P=0.039). Three patients had vertebral fractures (7%). pQCT values at the radius (4 and 66% sites) for bone area, vBMD, or strength strain index Z-scores did not differ between patients and controls. In contrast, at the tibial sites (4 and 38%), patients had significantly lower trabecular vBMD (mg/cm³, 216 (134–323) vs 235 (161–369), P=0.028) and lower cortical thickness (mm, 4.95 (3.37–5.86) vs 5.46 (2.76–7.32), P<0.001) than the control subjects. Total bone area did not differ between the groups.

Conclusion: Childhood-onset APECED with multiple risk factors constitutes a significant risk for bone health, associates with increased fracture risk and warrants careful follow-up of the patients already during childhood.

Disclosure: The authors declared no competing interests.