Epigenetic developmental programming and intergenerational effects of thyroid hormones.

Mounting evidence is showing that altered signaling through the nuclear hormone receptor superfamily can cause abnormal, long-term epigenetic changes which translate into pathological modifications and susceptibility to disease. These effects seem to be more prominent if the exposure occurs early in life, when transcriptomic profiles are rapidly changing. At this time, the coordination of the complex coordinated processes of cell proliferation and differentiation that characterize mammalian development.

Tafamidis polyneuropathy amelioration requires modest increases in transthyretin stability even though increases in plasma native TTR and decreases in non-native TTR do not predict response.

Background: TTR aggregation causes hereditary transthyretin (TTR) polyneuropathy (ATTRv-PN) in individuals with destabilised TTR variants. ATTRv-PN can be treated with ligands that bind TTR and prevent aggregation. One such ligand, tafamidis, is widely approved to treat ATTRv-PN.

Early onset obesity due to a mutation in the human leptin receptor gene.

Summary: Leptin is secreted by adipocytes in response to fat storage and binds to its receptor (LEPR), which is ubiquitously expressed throughout the body. Leptin regulates energy expenditure and is anorexigenic. In this study, we describe the clinical and hormonal findings of three siblings with a personal history of rapid weight gain during the first months of life.

A case report of multiple endocrine neoplasia type 1 and autoimmune disease: Coincidence or correlation?

Rationale: Multiple Endocrine Neoplasia type 1 (MEN1) is a familial syndrome that results from the disruption of a tumor suppressor protein called MENIN. Its management is challenging, as MEN1 affects different endocrine tissues and predisposes to both benign and malignant tumors. MENIN-deficient cells have recently been recognized to play a role in triggering autoimmunity.

Successful long-term use of pioglitazone in Berardinelli-Seip lipodystrophy-associated diabetes.

Summary: Berardinelli-Seip congenital lipodystrophy (BSCL) is a rare autosomal recessive disease, characterized by the absence of subcutaneous adipose tissue, leptin deficiency and severe metabolic complications, such as insulin resistance, diabetes mellitus, and dyslipidemia. The most common mutation occurs in BCSL2 which encodes seipin, a protein involved in adipogenesis. We report a patient with BSCL who was diagnosed with diabetes at 11 years old.

Increased Hepatic Fat Content in Patients with Resistance to Thyroid Hormone Beta.

Thyroid hormone (TH) has important functions in controlling hepatic lipid metabolism. Individuals with resistance to thyroid hormone beta (RTHβ) who harbor mutations in the gene experience loss-of-function of thyroid hormone receptor beta (TRβ), which is the predominant TR isoform expressed in the liver. We hypothesized that individuals with RTHβ may have increased hepatic steatosis.

Physiologic Significance of Epigenetic Regulation of Thyroid Hormone Target Gene Expression.

Background: In previous publications, we have reported our findings demonstrating that exposure to high maternal levels of thyroid hormones (TH) has life-long effects on the wild-type (WT, without mutation) progeny of mothers with resistance to thyroid hormone beta (RTHβ). The mechanism of this epigenetic effect remains unclear.

Objectives: We reviewed the mechanisms involved in the epigenetic regulation of TH target genes and understand how they may explain the reduced sensitivity to TH in the WT progeny of RTHβ mothers.

3,5-T2-A Janus-Faced Thyroid Hormone Metabolite Exerts Both Canonical T3-Mimetic Endocrine and Intracrine Hepatic Action.

Over the last decades, thyroid hormone metabolites (THMs) received marked attention as it has been demonstrated that they are bioactive compounds. Their concentrations were determined by immunoassay or mass-spectrometry methods. Among those metabolites, 3,5-diiodothyronine (3,5-T2), occurs at low nanomolar concentrations in human serum, but might reach tissue concentrations similar to those of T4 and T3, at least based on data from rodent models.

Predictive model of response to tafamidis in hereditary ATTR polyneuropathy.

BACKGROUNDThe hereditary transthyretin (TTR) amyloidoses are a group of diseases for which several disease-modifying treatments are now available. Long-term effectiveness of these therapies is not yet fully known. Moreover, the existence of alternative therapies has resulted in an urgent need to identify patient characteristics that predict response to each therapy.

Reduced Sensitivity to Thyroid Hormone as a Transgenerational Epigenetic Marker Transmitted Along the Human Male Line.

Evidence for transgenerational epigenetic inheritance in humans is still controversial, given the requirement to demonstrate persistence of the phenotype across three generations. A previous study showed that exposure of human and mouse embryos to high maternal thyroid hormone (TH) concentrations not only affects the newborns but also subsequently reduces thyrotroph sensitivity to TH during adult life. The current investigation set out to determine if this epigenetic effect is transmitted by humans not exposed to high TH levels to their offspring.

Transient Expression in Islets During Pregnancy Correlates With β-Cell Survival, Revealing a Novel Candidate Gene in Gestational Diabetes Mellitus.

Transient expression was reported in mouse islets during gestation, whereas a genome-wide linkage and admixture mapping study highlighted as a candidate gene for diabetes mellitus (DM). We sought the significance of PAX8 expression in mouse and human islet biology. was induced in gestating mouse islets and in human islets treated with recombinant prolactin.

Prenatal Diagnosis of Resistance to Thyroid Hormone and Its Clinical Implications.

Context: Resistance to thyroid hormone-β (RTH-β) is an autosomal dominant disorder characterized by reduced sensitivity of target tissues to thyroid hormones (THs). Individuals with RTH-β have high TH levels usually due to mutations in the TH receptor-β (THRB) gene. The management of RTH-β during pregnancy is challenging, as wild-type (WT) fetuses born to RTH-β mothers have low birth weight and suppressed postnatal thyroid-stimulating hormone (TSH), due to intrauterine exposure to excess TH.

Fetal Exposure to High Maternal Thyroid Hormone Levels Causes Central Resistance to Thyroid Hormone in Adult Humans and Mice.

Context: Fetuses exposed to the high thyroid hormone (TH) levels of mothers with resistance to thyroid hormone beta (RTH-β), due to mutations in the THRB gene, have low birth weight and suppressed TSH.

Objective: Determine if such exposure to high TH levels in embryonic life has a long-term effect into adulthood.

Design: Observations in humans with a parallel design on animals to obtain a preliminary information regarding mechanism.

Transient neonatal diabetes due to a missense mutation (E227K) in the gene encoding the ATP-sensitive potassium channel (KCNJ11).

Neonatal diabetes is a monogenic form of diabetes. Herein, we report on a newborn presenting diabetic ketoacidosis at 17 days of life. A KCNJ11 mutation was identified.

A new PAX8 mutation causing congenital hypothyroidism in three generations of a family is associated with abnormalities in the urogenital tract.

Background: Although thyroid dysgenesis is the most common cause of congenital hypothyroidism (CH), its molecular basis remains largely elusive. Indeed, in only a minority of cases with thyroid dysgenesis (2%-3%) was it possible to identify an underlying genetic defect. The objective of this study was to screen the PAX8 gene and the PAX2 gene in a family with six cases of CH spanning three generations and presenting urogenital malformations.

Serum copper as a novel biomarker for resistance to thyroid hormone.

Thyroid hormone action is mediated by the thyroid hormone receptors TRα1 and TRβ. Defects in TRβ lead to RTH (resistance to thyroid hormone) β, a syndrome characterized by high levels of thyroid hormone and non-suppressed TSH (thyroid-stimulating hormone). However, a correct diagnosis of RTHβ patients is difficult as the clinical picture varies.

A large family with Carney complex caused by the S147G PRKAR1A mutation shows a unique spectrum of disease including adrenocortical cancer.

Context: Most tumors in Carney complex (CNC) are benign, including primary pigmented nodular adrenocortical disease (PPNAD), the main endocrine tumor in CNC. Adrenocortical cancer (AC) has never been observed in the syndrome. Herein, we describe a large Azorean family with CNC caused by a point mutation in the PRKAR1A gene coding for type 1-α (RIα) regulatory subunit of the cAMP-dependent protein kinase A, in which the index patient presented with AC.

Autoimmunity in patients with resistance to thyroid hormone.

Context: Resistance to thyroid hormone (RTH) is an inherited syndrome most often caused by thyroid hormone receptor beta (TRbeta) gene mutations. Given that autoimmune thyroid disease (AITD) is prevalent in the general population, its coexistence with RTH has been presumed coincidental. It was recently proposed that chronic TSH stimulation in RTH may induce an autoimmune response, thereby increasing the chance of their coexistence.

Fetal loss associated with excess thyroid hormone exposure.

Context: Maternal hypothyroidism and hyperthyroidism have deleterious effects on the outcome of pregnancy. While the effects of thyroid hormone (TH) deprivation on the fetus, independently from that on the mother, can be studied in infants with congenital hypothyroidism, this is not the case in those with fetal thyrotoxicosis.

Objective: To study the effects of TH excess on fetuses carried by mothers with resistance to TH (RTH) who are euthyroid despite high TH levels but who may carry normal fetuses that are exposed to high maternal hormone levels.

Regression of a large goiter in a patient with resistance to thyroid hormone by every other day treatment with triiodothyronine.

Resistance to thyroid hormone (RTH) is a syndrome of reduced responsiveness to thyroid hormone caused, in the majority of cases, by mutation in the thyroid hormone receptor (TR) beta gene. Partial compensation through increase synthesis and secretion of thyroid hormone is mediated through TSH and results in thyroid gland enlargement. Goiters are of variable size but are recalcitrant to surgical treatment, and tend to recur.