TSH Receptor Mutations Among a Consanguineous Community

Study Overview
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Brief Summary
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Resistance to thyrotropin (RTSH) is a condition of impaired responsiveness of the thyroid gland to TSH, characterized by elevated TSH, low or normal thyroid hormone levels, and hypoplastic or normal-sized thyroid gland. The aim of the present study was to evaluate the clinical course over time,the genotype-phenotype association and the frequency of two different TSH-receptor (TSHR) mutations in a highly consanguineous population of the town of Um-El-Fahem.

Detailed Description
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Resistance to thyrotropin (RTSH) is a syndrome involving reduced sensitivity to TSH. It is characterized by elevated TSH, absence of goiter (normal or hypoplastic thyroid gland) and normal to very low levels of thyroid hormones. The TSH-receptor (TSHR) gene is located on chromosome 14q31 and it consists of extracellular, trans-membrane and intracellular domains. Mutation in the TSHR may cause either gain or loss of function of the receptor. Loss-of-function mutations are autosomal-recessively inherited and lead to a spectrum of phenotypes, ranging from mild euthyroid hyperthyrotropinemia to severe congenital hypothyroidism (CH). Insensitivity to TSH depends on both the severity and location of the TSHR mutations. Since the first report of familial euthyroid hyperthyrotropinemia caused by a TSHR mutation, several cases of loss-of-function mutations of the TSHR have been reported however only a few reports on the outcome of patients affected with TSHR mutations. Whether the condition of euthyroid hyperthyrotropinemia leads to clinical hypothyroidism, remains stable or normalizes over time has yet to be elucidated. We recently described a unique novel TSHR-inactivating mutation located at the third extracellular loop that preferentially affected the inositol phosphate (IP) pathway in three sisters of Arab-Muslim decent that presented with euthyroid hyperthyrotropinemia. Further analysis of the extended family revealed additional members with TSHR syndrome phenotype carrying two different TSHR mutations. All the affected subjects live in the same town. The aim of the present study was to evaluate the clinical course over time, the genotype-phenotype association and the frequency of these two different TSHR mutations among the highly consanguineous population of the town of Um El Fahem.

Official Title
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The Prevalence of TSH Receptor Mutation Among the Arab Population of Israel

Conditions
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Hypothyroidism

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subjects belonging to extended family of the index case Exclusion Criteria:
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 1<br>Extended family members | |
| 2<br>Control- subjects from the same town without known thyroid diseases | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Two specific TSHR mutations |  | Finished | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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TSH Receptor, resistance TSH, Hyperthyrortropinemia