Thyroid Hormone Resistance Syndrome

The goal of this observational study is to learn about the neurological and cardiological phenotype of patients with resistance to thyroid hormone (RTH) syndromes beta and alpha (RTHß and RTHa) due to dominant negative variants in the genes encoding the thyroid hormone receptors alpha (THRA) and beta (THRB).
The main question[s] it aims to answer are:
Define frequency and improve early diagnosis for RTH syndromes
Developing tools to accelerate diagnosis of RTH syndromes
Development and validation of monitoring tools
Participants, recruited at neonatal screening or from cohorts of patients with unexplained specific neuro-cognitive or cardiovascular phenotypes will be submitted to biochemical and genetic investigations. In addition pluripotent stem cells will be generated from peripheral blood cells of RTHs patients and studied in vitro to understand the molecular mechanisms underlying neurological and cardiovascular consequences. In vitro and clinical data, will be correlated to identify biomarkers for monitoring treatment.

Thyroid hormones (TH) play a pivotal role in the development and function of the mammalian brain. Patients with impaired thyroid hormone transport into the brain tissue or in the case of defective local thyroid hormone receptor (collectively referred to as thyroid hormone resistance) subsequently experience psychomotor disabilities.
The "DEEPTYPE" registry has been established with the objective of intensifying the genotyping and, in particular, the neurological phenotyping of patients exhibiting deficiencies in either the thyroid hormone transporter (MCT8) or the thyroid hormone receptor alpha (THRα). The objective of this registry-based study is to enhance the diagnostic yield for MCT8 and THRα deficiencies by employing the serum fT3/fT4 ratio as a more sophisticated screening parameter. Furthermore, the investigators will study the genomic regulation of both genes and attempt to identify further coding and non-coding mutations that result in TH resistance. The patient registry "DEEPTYPE" will document the retrospective and prospective clinical data of identified children in a comprehensive manner. This will enable the identification of three key groups: (i) patients with non-coding mutations, (ii) patients with milder phenotypes presenting only with a subset of symptoms seen in both "classic" conditions, and (iii) patients who are ready for clinical trials.