ESPE Abstracts

Introduction: Mutations in the thyroid hormone (TH) transporter MCT8 result in MCT8 deficiency, which is characterized by severe intellectual and motor disability and high serum T3 concentrations inducing thyrotoxicity in peripheral tissues. At present, no effective treatment is available, although preclinical studies suggest that the T3 analog Triac is a promising candidate to i) normalize serum T3 levels and thus alleviate the thyrotoxicosis and ii) restore TH signaling in t...

Background: The Dutch HYPOthalamic and PITuitary gene (HYPOPIT) study investigates the genetic and non-genetic causes of isolated growth hormone deficiency (IGHD) and combined pituitary hormone deficiency (CPHD). Former projects within the HYPOPIT study showed that only a small minority of the Dutch IGHD and CPHD cases could be explained by mutations in GH1, GHRHR, HMGA2 and CDK6 in IGHD patients and PROP1, HESX1, POU1F1, LHX3</...

Background: Monocarboxylate transporter 8 (MCT8) is a specific transporter of triiodothyronine (T3). MCT8 gene mutations cause a rare X-linked disorder known as Allan–Herndon–Dudley syndrome, characterized by thyroid dysfunction (high T3, low T4, and normal/high TSH) and psychomotor retardation.Case report: A 4-year- and 9-month-old boy, who was already having L-T4 treatment fo...

Background: Patients with a mutation in the thyroid hormone (TH) receptor TRα1 are characterized by growth retardation, delayed bone development, mild cognitive defects and constipation. They also have abnormal TH levels: low FT4, high T3, and low rT3 levels, suggesting an altered peripheral TH metabolism by deiodinases. The type 3 deiodinase (D3) inactivates TH by catalyzing the degradation of T3. D3 is importantly expressed in...

Background: Recently, the first patients with resistance to thyroid hormone (RTHα) due to inactivating mutations in TRα1 have been identified. These patients are characterized by growth retardation, delayed bone development, mild cognitive defects, delayed motor development and abnormal thyroid function tests.Objective and hypotheses: We hypothesized that the phenotype of a TRα mutation depends on its location, e.g. if it is present only i...

Background: Recently, T3 receptor alpha (TRα) mutations have been identified in a number of patients with varying degrees of growth impairment, delayed development, constipation, increases in serum T3 and decreases in T4 and rT3.Objective: To determine the spectrum of clinical and functional consequences of novel TRα mutations.Method: Clinical assessment and biochemical, imaging...