Myopathy in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy

Hypoparathyroidism: Musculoskeletal Manifestations Related to Parathormone Deficiency

BACKGROUND

Hypoparathyroidism is a rare metabolic disorder that can be responsible for musculoskeletal manifestations.

AIM

We present a systematic review of musculoskeletal manifestations of adult-onset nonsurgical nongenetic hypoparathyroidism.

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline using the MEDLINE database, including manuscripts describing musculoskeletal manifestations of adult-onset nonsurgical nongenetic hypoparathyroidism.

RESULTS

Musculoskeletal manifestations included myopathy, shoulder disorder, immune-negative non-erosive peripheral arthritis, axial involvement simulating spondylarthritis, and diffuse ligamentous ossifications. An association between hypoparathyroidism and spondyloarthritis or autoimmune diseases is possible. T-cell activation, seen in patients with hypoparathyroidism, may explain the co-occurrence of hypoparathyroidism with other autoimmune diseases. The treatment of these manifestations is based on calcium and active vitamin D supplementation. Parathyroid hormone may have an anabolic effect on muscle atrophy and muscle weakness. Parathyroid hormone can also promote bone formation and bone resorption by stimulating osteoclast differentiation by increasing RANKL (receptor activator for nuclear factor kappa-B ligand) expression. Therefore, hypoparathyroidism can be responsible for an increase in bone mineral density. However, the risk of fractures does not appear to be reduced due to changes in bone microarchitecture and the high risk of falls. Treatment with parathyroid hormone has been shown to improve bone microarchitecture.

CONCLUSION

Our review showed that musculoskeletal manifestations are frequent in patients with hypoparathyroidism, including muscular, axial, peripheral articular, and entheseal manifestations.

Case report: Discovery of a de novo FAM111B pathogenic variant in a patient with an APECED-like clinical phenotype

Introduction

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) and poikiloderma in association with tendon contractures, myopathy, and pulmonary fibrosis (POIKTMP) are rare inherited syndromes resulting from biallelic pathogenic variants in AIRE and heterozygous pathogenic variants in FAM111B, respectively. The clinical diagnosis of APECED and POIKTMP rely on the development of two or more characteristic disease manifestations that define the corresponding syndromes. We discuss the shared and distinct clinical, radiographic, and histological features between APECED and POIKTMP presented in our patient case and describe his treatment response to azathioprine for POIKTMP-associated hepatitis, myositis, and pneumonitis.

Methods

Through informed consent and enrollment onto IRB-approved protocols (NCT01386437, NCT03206099) the patient underwent a comprehensive clinical evaluation at the NIH Clinical Center alongside exome sequencing, copy number variation analysis, autoantibody surveys, peripheral blood immunophenotyping, and salivary cytokine analyses.

Results

We report the presentation and evaluation of a 9-year-old boy who was referred to the NIH Clinical Center with an APECED-like clinical phenotype that included the classic APECED dyad of CMC and hypoparathyroidism. He was found to meet clinical diagnostic criteria for POIKTMP featuring poikiloderma, tendon contractures, myopathy, and pneumonitis, and exome sequencing revealed a de novo c.1292T>C heterozygous pathogenic variant in FAM111B but no deleterious single nucleotide variants or copy number variants in AIRE.

Discussion

This report expands upon the available genetic, clinical, autoantibody, immunological, and treatment response information on POIKTMP.

French-Canadian families from Saguenay-Lac-Saint-Jean: a new founder population for APECED

PURPOSE

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is more prevalent in some founder populations, but relatively unexplored in Canada. This study aimed at investigating the French-Canadian patients through phenotypic and genotypic characterization.

METHOD

Phenotype and demographic characterization were done for 12 affected individuals belonging to eight unrelated families. Samples from 11 cases were analyzed in a molecular clinical laboratory, and muscle biopsies were reviewed for two individuals with a limb-girdle muscle dystrophy.

RESULTS

The clinical phenotype was similar to that observed in European Caucasian populations but differed in the non-endocrine spectrum from the American-reported series of cases. Two cases exhibited a limb-girdle muscle dystrophy, and we found preliminary evidence of a mitochondrial dysfunction, since all three biopsies examined showed COX-deficient fibers in excess of what would be expected for age. Electron microscopy showed mitochondrial accumulation without abnormal cristea or inclusions. The c.1616C > T variant in the AIRE gene was responsible for 100% of APECED cases in the French-Canadian population of Saguenay-Lac-Saint-Jean in Quebec, Canada.

CONCLUSIONS

We report the first series of French-Canadian cases affected with APECED. The Saguenay-Lac-Saint-Jean region was uncovered as a new founder population for this condition. Muscle biopsy findings expanded the range of previously described APECED-related myopathology. Long term follow-up of our genetically homogeneous French-Canadian cases may help determine if the c.1616C > T variant increases the risk of muscle involvement. A neonatal screening program is under consideration to prevent undesired life-threatening endocrine manifestations.

A case report and literature review: Identification of a novel AIRE gene mutation associated with Autoimmune Polyendocrine Syndrome Type 1 in East Asians

RATIONALE

Autoimmune polyendocrine syndrome type 1 (APS-1), also referred as the autoimmune polyendocrinopathy candidiasis-ectodermal dystrophy (APECED), is a rare autosomal inherited disease predominantly among Caucasians from Northern Europe. This syndrome is very rare in East Asian population.

PATIENTS CONCERNS

Here, we describe a case of a 15-year-old Chinese boy admitted due to a 1-month history of intermittent fatigue, nausea, vomiting, and diarrhea. His symptom became worse accompanied with chest tightness 4 days before admission. On physical examination, his temperature was 38.5°C, blood pressure was 75/38 mm Hg, and pulse was 98/min. He was a thin boy with mild hyperpigmentation and xanthochromia.

DIAGNOSIS

After abdominal computed technology and laboratory tests, his diagnosis was APS-1 accompanied with adrenal crisis. Further investigation on whole-exome sequencing revealed a novel homozygous mutation c.47C>G (p.T16R) in exon 1 in the autoimmune regulator (AIRE) gene.

INTERVENTIONS

This patient underwent replacement therapy of glucocorticoids, corticosteroid, and levothyroxine, as well as calcium and calcitriol supplementation.

OUTCOMES

He continues to do well 4 years after his hospitalization. During his last follow-up, he had serum thyroid-stimulating hormone level of 3.07 μIU/mL, free triiodothyronine level of 1.92 pg/mL, and free thyroxine level of 13.95 pg/mL. His serum cortisol and ACTH (8 a.m.) levels were 28.53 μg/dL and 69.48 pg/mL, respectively.

LESSONS

APS-1 is very rare in East Asians and the variable clinical presentations of the disease make the initial diagnosis especially difficult. Autoimmune thyroiditis, type 1 diabetes mellitus, and hepatitis were the three most frequent minor components of APS-1 in East Asian patients with age of onset in late teens and 20s. Sequence analysis of AIRE gene is necessary to verify its diagnostic efficacy in association with clinical findings.

Reduction of Total Brain and Cerebellum Volumes Associated With Neuronal Autoantibodies in Patients With APECED

CONTEXT

In autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), autoantibodies (AutoAbs) labeling brain neurons were reported; conversely, brain MRI alterations associated with these AutoAbs were never reported.

OBJECTIVES

To describe brain alterations in APECED and to correlate them with AutoAbs against glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH), and 5-tryptophan hydroxylase (5-HT) neurons.

DESIGN AND PARTICIPANTS

Fourteen Sardinian patients with APECED and age-matched control subjects were recruited for MRI analysis and blood sampling to detect AutoAbs to GAD, TH, and 5-HT neurons by using rat brain sections. The majority of patients (n = 12) were investigated for AutoAbs a decade earlier, and 7 of 12 were positive for AutoAbs to GAD and TH neurons.

MAIN OUTCOMES

Patients with APECED had smaller cerebellum and gray matter volumes, with a ventricular enlargement and a total cerebrospinal fluid (CSF) increase, compared with controls (P < 0.01). In 11 of 14 patients, brain abnormalities were associated with AutoAbs to GAD or TH neurons (titer 1:100 to 15,000) that had persisted for 10 years in 7 of 11 patients. AutoAbs to 5-HT neurons were revealed in all patients with AutoAbs to TH neurons. A decrease in whole brain and cerebellum volumes (P = 0.028) was associated with AutoAbs to GAD neurons, and a CSF increase was associated with AutoAbs to GAD and TH/5-HT neurons (P < 0.05). HLA alleles did not appear to be involved in neuronal autoimmunity.

CONCLUSIONS

Brain alterations and neuronal AutoAbs were observed in 78.6% of Sardinian patients with APECED, suggesting a brain autoimmune reaction. Prolonged clinical follow-up must be conducted for the possible appearance of clinical neurologic consequences.

Novel Findings into AIRE Genetics and Functioning: Clinical Implications

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), formerly known as autoimmune polyendocrine syndrome type 1, is a paradigm of a monogenic autoimmune disease caused by mutations of a gene, named autoimmune regulator (AIRE). AIRE acts as a transcription regulator that promotes immunological central tolerance by inducing the ectopic thymic expression of many tissue-specific antigens. Although the syndrome is a monogenic disease, it is characterized by a wide variability of the clinical expression with no significant correlation between genotype and phenotype. Indeed, many aspects regarding the exact role of AIRE and APECED pathogenesis still remain unraveled. In the last decades, several studies in APECED and in its mouse experimental counterpart have revealed new insights on how immune system learns self-tolerance. Moreover, novel interesting findings have extended our understanding of AIRE's function and regulation thus improving our knowledge on the pathogenesis of APECED. In this review, we will summarize recent novelties on molecular mechanisms underlying the development of APECED and their clinical implications.

Regulation of human autoimmune regulator (AIRE) gene translation by miR-220b

Although mutations of autoimmune regulator (AIRE) gene are responsible for autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), presenting a wide spectrum of many characteristic and non-characteristic clinical features, some patients lack AIRE gene mutations. Therefore, something other than a mutation, such as dysregulation of AIRE gene, may be a causal factor for APECED or its related diseases. However, regulatory mechanisms for AIRE gene expression and/or translation have still remained elusive. We found that IL-2-stimulated CD4(+) T (IL-2T) cells showed a high expression of AIRE gene, but very low AIRE protein production, while Epstein-Barr virus-transformed B (EBV-B) cells express both AIRE gene and AIRE protein. By using microarray analysis, we could identify miR-220b as a possible regulatory mechanism for AIRE gene translation in IL-2T cells. Here we report that miR-220b significantly reduced the expression of AIRE protein in AIRE gene with 3'UTR region transfected 293T cells, whereas no alteration of AIRE protein production was observed in the open reading frame of AIRE gene alone transfected cells. In addition, anti-miR-220b reversed the inhibitory function of miR-220b for the expression of AIRE protein in AIRE gene with 3'UTR region transfected cells. Moreover, when AIRE gene transfected cells with mutated 3'UTR were transfected with miR-220b, no reduction of AIRE protein production was observed. Taken together, it was concluded that miR-220b inhibited the AIRE gene translation through the 3'UTR region of AIRE gene, indicating that miR-220b could serve as a regulator for human AIRE gene translation.

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy: insights into genotype-phenotype correlation

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is a rare autosomal recessive disease, caused by mutations of a single gene named autoimmune regulator gene (AIRE) which results in a failure of T cell tolerance within the thymus. Chronic mucocutaneous candidiasis, chronic hypoparathyroidism, and Addison's disease are the hallmarks of the syndrome. APECED is also characterized by several autoimmune endocrine and nonendocrine manifestations, and the phenotype is often complex. Moreover, even though APECED is a monogenic disease, its clinical picture is generally dominated by a wide heterogeneity both in the severity and in the number of components even among siblings with the same AIRE genotype. The variability of its clinical expression implies that diagnosis can be challenging, and a considerable delay often occurs between the appearance of symptoms and the diagnosis. Since a prompt diagnosis is essential to prevent severe complications, clinicians should be aware of all symptoms and signs of suspicion. The aim of this paper is to give an overview on the clinical presentation and diagnostic criteria of APECED and to focus on current knowledge on genotype-phenotype correlation.