Sahoo SK, Zaidi G, Srivastava R, Sarangi AN, Bharti N, Eriksson D, Bensing S, Kämpe O, Aggarwal A, Aggarwal R, Bhatia E
Clin. Endocrinol. (Oxf) 85 (4) 544-550 [2016-10-00; online 2016-06-28]
The prevalence of autoimmune polyendocrine syndrome type 1 (APS1) among isolated hypoparathyroidism (HP) or primary adrenal insufficiency (PAI) is not well established. We studied the frequency of APS1 in patients with HP or PAI by measuring interferon-α (IFN-α) antibody levels, a highly sensitive and specific marker for APS1. In a single-centre cross-sectional study, 37 Indian patients with isolated HP and 40 patients with PAI were tested for IFN-α antibody using an indirect ELISA. In patients with elevated IFN-α antibody, the autoimmune regulator (AIRE) gene was bidirectionally sequenced. Three (8·1%) patients with isolated HP had elevated IFN-α antibody levels (range: 367-17382 units; positive titre >56 units). Homozygous or compound heterozygous AIRE mutations were detected in all three patients, including a novel mutation (p.T68P). All three APS1 patients had atypical features. The first patient, diagnosed at 7 years of age, died suddenly 5 months later. The second patient had late-onset HP (at the age of 34 years) and a solitary episode of transient mucocutaneous candidiasis 5 years later. The final patient developed HP at the age of 14 years and premature ovarian insufficiency 14 years later. Interleukin-22 antibodies, as well as most other organ-specific antibodies, were absent in the 3 APS1 patients. All patients with PAI were negative for IFN-α antibody. Eight percentage of patients with isolated HP had elevated IFN-α antibody levels and AIRE mutation-positive APS1. All APS1 patients had atypical clinical features. Testing for IFN-α antibody should be considered in patients with idiopathic HP.