Identification of autoimmune polyendocrine syndrome type 1 in patients with isolated hypoparathyroidism

Selected Genetic Factors Associated with Primary Ovarian Insufficiency

Primary ovarian insufficiency (POI) is a heterogeneous disease resulting from non-functional ovaries in women before the age of 40. It is characterized by primary amenorrhea or secondary amenorrhea. As regards its etiology, although many POI cases are idiopathic, menopausal age is a heritable trait and genetic factors play an important role in all POI cases with known causes, accounting for approximately 20% to 25% of cases. This paper reviews the selected genetic causes implicated in POI and examines their pathogenic mechanisms to show the crucial role of genetic effects on POI. The genetic factors that can be found in POI cases include chromosomal abnormalities (e.g., X chromosomal aneuploidies, structural X chromosomal abnormalities, X-autosome translocations, and autosomal variations), single gene mutations (e.g., newborn ovary homeobox gene (NOBOX), folliculogenesis specific bHLH transcription factor (FIGLA), follicle-stimulating hormone receptor (FSHR), forkhead box L2 (FOXL2), bone morphogenetic protein 15 (BMP15), etc., as well as defects in mitochondrial functions and non-coding RNAs (small ncRNAs and long ncRNAs). These findings are beneficial for doctors to diagnose idiopathic POI cases and predict the risk of POI in women.

The natural history of 21-hydroxylase autoantibodies in autoimmune Addison's disease

BACKGROUND

The most common cause of primary adrenal failure (Addison's disease) in the Western world is autoimmunity characterized by autoantibodies against the steroidogenic enzyme 21-hydroxylase (CYP21A2, 21OH). Detection of 21OH-autoantibodies is currently used for aetiological diagnosis, but how levels of 21OH-autoantibodies vary over time is not known.

SETTING

Samples from the national Norwegian Addison's Registry and Biobank established in 1996 (n = 711). Multi-parameter modelling of the course of 21OH-autoantibody indices over time.

RESULTS

21OH-autoantibody positivity is remarkably stable, and >90% of the patients are still positive 30 years after diagnosis. Even though the antibody levels decline with disease duration, it is only rarely that this downturn reaches negativity. 21OH-autoantibody indices are affected by age at diagnosis, sex, type of Addison's disease (isolated vs autoimmune polyendocrine syndrome type I or II) and HLA genotype.

CONCLUSION

21OH-autoantibodies are reliable and robust markers for autoimmune Addison's disease, linked to HLA risk genotype. However, a negative test in patients with long disease duration does not exclude autoimmune aetiology.

Autoimmune polyendocrine syndrome type 1 (APECED) in the Indian population: case report and review of a series of 45 patients

BACKGROUND

Autoimmune polyendocrinopathy-candidiasis-ectodermal-dystrophy (APECED) or autoimmune polyglandular syndrome type 1 (APS-1) is a rare autosomal recessive genetic disease due to mutations in the AIRE (AutoImmune REgulator) gene. The clinical diagnosis is classically based on the presence of at least two of the three main components: chronic mucocutaneous candidiasis, hypoparathyroidism and primary adrenal insufficiency. Patients often suffer from other endocrine or non-endocrine autoimmune conditions throughout life. APECED etiopathogenesis is mediated by T lymphocytes. Autoantibodies against proteins of the affected organs are found in the serum of APECED patients as well as neutralizing antibodies against cytokines. We report here the clinical and genetic characteristics of 45 Indian APECED patients in comparison to Finnish, Sardinian, Turkish and North/South American cohorts from their published results. We also report a new case of APECED of Indian origin, a 2-year old child suffering from chronic mucocutaneous candidiasis since the age of 8 months, with confirmatory AIRE homozygous mutation c.274C > T (p.R92W).

CONCLUSION

With the inherent limitations of a retrospective study, analysis of Indian APECED patients suggested that compared to classic criteria, application of Ferre/Lionakis criteria validated in North/South American patients could help in earlier diagnosis in 3 of 8 (37.5%) patients for whom adequate information for evaluation was available.

Lessons from primary immunodeficiencies: Autoimmune regulator and autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy

The discovery of the autoimmune regulator (AIRE) protein and the delineation of its critical contributions in the establishment of central immune tolerance has significantly expanded our understanding of the immunological mechanisms that protect from the development of autoimmune disease. The parallel identification and characterization of patient cohorts with the monogenic disorder autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), which is typically caused by biallelic AIRE mutations, has underscored the critical contribution of AIRE in fungal immune surveillance at mucosal surfaces and in prevention of multiorgan autoimmunity in humans. In this review, we synthesize the current clinical, genetic, molecular and immunological knowledge derived from basic studies in Aire-deficient animals and from APECED patient cohorts. We also outline major advances and research endeavors that show promise for informing improved diagnostic and therapeutic approaches for patients with APECED.

Medical Hypoparathyroidism

Hypoparathyroidism is a metabolic disorder characterized by hypocalcemia, hyperphosphatemia, and inadequate levels of or function of parathyroid hormone (PTH). The authors review the nonsurgical or medical causes of hypoparathyroidism. The most common of the nonsurgical causes is autoimmune destruction of the parathyroid. Magnesium deficiency or excess can cause a functional hypoparathyroidism. Genetic conditions result in hypoparathyroidism as part of a syndrome or in isolation. Pseudohypoparathyroidism reflects a resistance to PTH. Infiltrative, metastatic, radiation destruction, mineral deposition, or idiopathic are uncommon causes of hypoparathyroidism. This article reviews the causes of hypoparathyroidism and an approach to the evaluation of this condition.

Incidence of parathyroid disorders in Indian adult male population: A 25-year follow-up study

CONTEXT AND OBJECTIVE

Detailed information on the epidemiology of parathyroid disorders in India is lacking. Most of the available data pertain to primary hyperparathyroidism (PHPT) rather than the overall burden of parathyroid disorders. We studied the incidence of parathyroid disorders in a cohort of service personnel followed for a long duration.

DESIGN, SETTING AND PATIENTS

The data for this retrospective, descriptive epidemiological study were derived from the electronic medical records (EMR) of health care personnel enrolled between 1990 and 2015. Subjects were recruited between the ages of 17 and 20 years in good health, and the data pertaining to parathyroid disorders were derived from the EMR.

MAIN OUTCOMES MEASURES

We calculated the incidence rates per person-years of parathyroid disorders using appropriate statistical methods.

RESULTS

Our analysis includes 51 217 participants (median age 33, range 17-54 years) with a mean follow-up of 12.5 years. Yearly evaluation of the data gave cumulative follow-up duration of 613 925 person-years. PHPT was diagnosed in 37 patients and hypoparathyroidism in 16 patients, giving incidence rates of 6 and 2.6 per 100 000 person-years, respectively. Only one patient was diagnosed with pseudohypoparathyroidism (0.16 per 100 000 person-years). Of the 37 patients with PHPT, 16 (43%) developed postsurgical hypoparathyroidism.

CONCLUSIONS

Our cohort had a low incidence of PHPT when compared to Western populations. Long-term epidemiological studies are essential to identify the demographic trends of metabolic bone disorders in India.

Autoimmune polyendocrine syndrome type 1 in an Indian cohort: a longitudinal study

OBJECTIVE

Autoimmune polyendocrine syndrome type 1 (APS1) is a rare autosomal recessive disorder characterized by progressive organ-specific autoimmunity. There is scant information on APS1 in ethnic groups other than European Caucasians. We studied clinical aspects and autoimmune regulator (AIRE) gene mutations in a cohort of Indian APS1 patients.

DESIGN

Twenty-three patients (19 families) from six referral centres in India, diagnosed between 1996 and 2016, were followed for [median (range)] 4 (0.2-19) years.

METHODS

Clinical features, mortality, organ-specific autoantibodies and AIRE gene mutations were studied.

RESULTS

Patients varied widely in their age of presentation [3.5 (0.1-17) years] and number of clinical manifestations [5 (2-11)]. Despite genetic heterogeneity, the frequencies of the major APS1 components (mucocutaneous candidiasis: 96%; hypoparathyroidism: 91%; primary adrenal insufficiency: 55%) were similar to reports in European series. In contrast, primary hypothyroidism (23%) occurred more frequently and at an early age, while kerato-conjunctivitis, urticarial rash and autoimmune hepatitis were uncommon (9% each). Six (26%) patients died at a young age [5.8 (3-23) years] due to septicaemia, hepatic failure and adrenal/hypocalcaemic crisis from non-compliance/unexplained cause. Interferon-α and/or interleukin-22 antibodies were elevated in all 19 patients tested, including an asymptomatic infant. Eleven AIRE mutations were detected, the most common being p.C322fsX372 (haplotype frequency 37%). Four mutations were novel, while six others were previously described in European Caucasians.

CONCLUSIONS

Indian APS1 patients exhibited considerable genetic heterogeneity and had highly variable clinical features. While the frequency of major manifestations was similar to that of European Caucasians, other features showed significant differences. A high mortality at a young age was observed.

Exome Sequencing Reveals Mutations in AIRE as a Cause of Isolated Hypoparathyroidism

Context

Most cases of autosomal recessive hypoparathyroidism (HYPO) are caused by loss-of-function mutations in GCM2 or PTH.

Objective

The objective of this study was to identify the underlying genetic basis for isolated HYPO in a kindred in which 3 of 10 siblings were affected.

Subjects

We studied the parents and the three adult affected subjects, each of whom was diagnosed with HYPO in the first decade of life.

Methods

We collected clinical and biochemical data and performed whole exome sequencing analysis on DNA from the three affected subjects after negative genetic testing for known causes of HYPO.

Results

Whole exome sequencing followed by Sanger sequencing revealed that all three affected subjects were compound heterozygous for two previously reported mutations, c.967_979delCTGTCCCCTCCGC:p.(L323SfsX51) and c.995+(3_5)delGAGinsTAT, in AIRE, which encodes the autoimmune regulator protein that is defective in autoimmune polyglandular syndrome type 1 (APS-1). Each parent carries one mutation, and all of the children of the patients are either heterozygous for one mutation or wild type. The affected sister developed premature ovarian failure, but the two affected brothers have no other features of APS-1 despite elevated serum levels of anti-interferon-α antibodies.

Conclusions

Our findings indicate that biallelic mutations in AIRE can cause isolated HYPO as well as syndromic APS-1. The presence of antibodies to interferon-α provides a highly sensitive indicator for loss of AIRE function and represents a useful marker for isolated HYPO due to AIRE mutations.