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A New Point Mutation (A420G) in the Thyroid Hormone Receptor-β Gene of a Patient with Resistance to Thyroid Hormone

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Title: A New Point Mutation (A420G) in the Thyroid Hormone Receptor-β Gene of a Patient with Resistance to Thyroid Hormone
Authors: Villadolid, Maria C.
Issue Date: 11-Dec-1995
Citation: Acta medica Nagasakiensia. 1995, 40(1-4), p.1-6
Abstract: Resistance to thyroid hormone (RTH) is a syndrome of reduced responsiveness of tissues to thyroid hormone. We present a new point mutation at nucleotide 1544 of the T_3 binding region of thyroid hormone receptor-β(TR β) resulting in a lysine to arginine substitution in codon 420 in a female patient diagnosed with RTH in Nagasaki, Japan. The clinical characteristics of this patient is extremely milder than those reported in other families with RTH, namely goiter, tachycardia, and learning disability. On the other hand, the thyroid function tests are typical of other subjects with RTH and TSH levels were not suppressed even when supraphysiologic doses of T_3 (75 μg/day for 7 days) were given. Basal peripheral tissue response parameter levels did not alter even after administration of T_3. Thyrotropinreleasing hormone (TRH), 200 μg i.v., caused a rise in TSH, T_3 and T_4, indicating that the pituitary-thyroid system was intact and the patient's TSH was biologically active. To further confirm the biological activity of this mutant TRβ,amutant TR,β gene chimera was constructed in vitro using the Spliced Overlap Extension Method. In vitro translation product of this mutant TR β gene demonstrated 40% reduction in binding capacity compared to the wild type. It is now known that thyroid hormone resistance presents with a wide spectrum of phenotypes accompanying the presence of point mutations in different areas of the T_3 binding domain of the TR β gene. These data suggest that a subclinical RTH with familial or sporadic cases may also possess a point mutation of TR β as well as typical RTH.
URI: http://hdl.handle.net/10069/16033
ISSN: 00016055
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:Volume 40, No. 1-4

Citable URI : http://hdl.handle.net/10069/16033

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