A novel missense mutation in the AIRE gene underlying autoimmune polyglandular syndrome type 1.

The immune regulator gene AIRE plays an essential role in the establishment of immune tolerance and the prevention of autoimmunity. This transcription factor plays a critical role in promoting self-tolerance in the thymus by regulating the expression of a large number of self-antigens that share the common feature of being tissue-restricted in their expression pattern in the periphery. Dysfunction of AIRE in humans causes a rare disease, autoimmune polyglandular syndrome type 1 (APS1), characterized by an autoimmune response against peripheral tissues, particularly endocrine tissues. Although a few dominant mutations have been described, the inactivation of AIRE is usually caused by recessive mutations. Recent data suggests that alterations in AIRE function contribute not only to APS1 but also to more common forms of autoimmune disease. Here, we present a previously unreported missense mutation (NM_000383.2:c.260 T > C) in exon 2 of the AIRE gene, predicted to cause the substitution (p.(Leu87Pro)) in the CARD domain of the AIRE protein. When inherited in conjunction with another dysfunctional AIRE allele, this mutation was associated with immune dysregulation in a pediatric patient. The presence of hypergammaglobulinemia, malabsorption syndrome, ectodermal dysplasia, mucocutaneous candidiasis, vitiligo, and hypothyroidism as well as the presence of multiple autoantibodies allowed us to confirm an APS1 diagnosis.

The AIRE G228W mutation disturbs the interaction of AIRE with its partner molecule SIRT1.

The autoimmune regulator (AIRE) protein functions as a tetramer, interacting with partner proteins to form the "AIRE complex," which relieves RNA Pol II stalling in the chromatin of medullary thymic epithelial cells (mTECs). AIRE is the primary mTEC transcriptional controller, promoting the expression of a large set of peripheral tissue antigen genes implicated in the negative selection of self-reactive thymocytes. Under normal conditions, the SIRT1 protein temporarily interacts with AIRE and deacetylates K residues of the AIRE SAND domain. Once the AIRE SAND domain is deacetylated, the binding with SIRT1 is undone, allowing the AIRE complex to proceed downstream with the RNA Pol II to the elongation phase of transcription. Considering that the in silico and in vitro binding of the AIRE SAND domain with SIRT1 provides a powerful model system for studying the dominant SAND G228W mutation mechanism, which causes the autoimmune polyglandular syndrome-1, we integrated computational molecular modeling, docking, dynamics between the whole SAND domain with SIRT1, and surface plasmon resonance using a peptide harboring the 211 to 230 residues of the SAND domain, to compare the structure and energetics of binding/release between AIRE G228 (wild-type) and W228 (mutant) SAND domain to SIRT1. We observed that the G228W mutation in the SAND domain negatively influences the AIRE-SIRT1 interaction. The disturbed interaction might cause a disruption in the binding of the AIRE SAND domain with the SIRT1 catalytic site, impairing the AIRE complex to proceed downstream with RNA Pol II.

Long-Term Parathyroid Hormone 1-34 Replacement Therapy in Children with Hypoparathyroidism.

OBJECTIVE: To determine whether multiple daily injections of parathyroid hormone (PTH) 1-34 are safe and effective as long-term therapy for children with hypoparathyroidism. STUDY DESIGN: Linear growth, bone accrual, renal function, and mineral homeostasis were studied in a long-term observational study of PTH 1-34 injection therapy in 14 children. METHODS: Subjects were 14 children with hypoparathyroidism attributable to autoimmune polyglandular syndrome type 1 (N = 5, ages 7-12 years) or calcium receptor mutation (N = 9, ages 7-16 years). Mean daily PTH 1-34 dose was 0.75 ± 0.15 µg/kg/day. Treatment duration was 6.9 ± 3.1 years (range 1.5-10 years). Patients were evaluated semiannually at the National Institutes of Health Clinical Center. RESULTS: Mean height velocity and lumbar spine, whole body, and femoral neck bone accretion velocities were normal throughout the study. In the first 2 years, distal one-third radius bone accrual velocity was reduced compared with normal children (P < .003). Serum alkaline phosphatase correlated with PTH 1-34 dose (P < .006) and remained normal (235.3 ± 104.8 [SD] U/L, N: 51-332 U/L). Mean serum and 24-hour urine calcium levels were 2.05 ± 0.11 mmol/L (N: 2.05-2.5 mmol/L) and 6.93 ± 1.3 mmol/24 hour (N: 1.25-7.5 mmol/24 hour), respectively-with fewer high urine calcium levels vs baseline during calcitriol and calcium treatment (P < .001). Nephrocalcinosis progressed in 5 of 12 subjects who had repeated renal imaging although renal function remained normal. CONCLUSIONS: Twice-daily or thrice-daily subcutaneous PTH 1-34 injections provided safe and effective replacement therapy for up to 10 years in children with hypoparathyroidism because of autoimmune polyglandular syndrome type 1 or calcium receptor mutation.

The heterogeneity of autoimmune polyendocrine syndrome type 1: Clinical features, new mutations and cytokine autoantibodies in a Brazilian cohort from tertiary care centers.

Autoimmune polyendocrine syndrome type 1 (APS1) is characterized by multiorgan autoimmunity. We aim at characterizing a multi-center Brazilian cohort of APS1 patients by clinical evaluation, searching mutation in the AIRE gene, measuring serum autoantibodies, and investigating correlations between findings. We recruited patients based on the clinical criteria and tested them for AIRE mutations, antibodies against interferon type I and interleukins 17A, 17F and 22. We identified 12 unrelated families (13 patients) with typical signs of APS1 in the proband, and the screening of relatives recognized an asymptomatic child. Candidiasis was present in all cases, and 19 other manifestations were observed. All patients carried one of 10 different mutations in AIRE, being 3 new ones, and were positive for anti-interferon type I serum antibody. Anti-interleukin-17A levels inversely correlated with the number of manifestations in each patient. This negative correlation may suggest a protective effect of anti-interleukin-17A with a potential therapeutic application.