Endocrine Abstracts

Context: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is caused by mutations in the autoimmune regulator (AIRE) gene and is characterised by the presence of chronic mucocutaneous candidiasis, hypoparathyroidism and Addison’s disease. Patients typically display organ-specific autoantibodies which correlate with a particular clinical manifestation. Previous studies have identified the parathyroid-expressed calcium-sensing receptor (CaSR) as an autoantibody target in APECED. However, it is unclear if antibodies against the CaSR correlate with APECED-associated hypoparathyroidism.

Objective: To identify associations between the presence of CaSR antibodies and the disease manifestations and demographic characteristics of APECED patients.

Design, subjects and methods: This was a case–control study including 44 APECED patients and 38 healthy control subjects. Antibodies against the CaSR were detected using immunoprecipitation assays.

Results: CaSR antibodies were detected in 16 out of 44 (36%) APECED patients and in none of 23 (0%) healthy control subjects (P≤0.0001). No statistically significant associations were found between the presence of CaSR antibodies and the disease manifestations of APECED including hypoparathyroidism (P values were >0.05). The detection of CaSR antibodies had a specificity of 83%, and a sensitivity of 39% for the diagnosis of hypoparathyroidism. There were no significant associations between the presence of CaSR antibodies and either sex, age or disease presentation age (P values were >0.05). However, a significant association between a shorter APECED duration (<10 years) and positivity for CaSR antibodies was noted (P=0.019).

Conclusion: CaSR antibodies were not found to be a specific or sensitive marker for hypoparathyroidism in APECED. Further investigations are required to determine the exact role of the autoimmune response against the CaSR in the pathogenesis of this autoimmune syndrome.