Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Five families with familial inherited TSH deficiency, reported to date, were examined for the TSH beta gene at the nucleotide level. The first family carries a single base substitution in the 29th codon which lies in the so-called CAGYC region; GCA (glycine) is replaced by AGA (arginine). This substitution induces conformational changes of the beta-polypeptide which make it unable to associate with the alpha-subunit. This mutation generates a new cleavage site for a restriction endonuclease MaeI, a new marker that can be used for DNA diagnosis. The second and third families were found to carry the same nucleotide substitution. Also, all three families were associated with an additional single base substitution in intron 2 as a polymorphic change, suggesting that these three families may have originated from the same single founder from Shikoku Island in Japan. The nucleotide sequence from the fourth and fifth families showed no alterations in the TSH beta gene from the about -200 basepair up-stream region to the polyadenylation site.
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PMID:Deoxyribonucleic acid analyses of five families with familial inherited thyroid stimulating hormone deficiency. 240 10

We identified a new nonsense mutation of the TSH-beta subunit gene responsible for a severe isolated TSH deficiency in two children from the same consanguineous kindred. These affected children are homozygous for a C-to-T transition at nucleotide 654 of the TSH-beta subunit gene, leading to the conversion of a glutamine (CAG) to a premature stop codon (TAG) in the codon 49 (Q49X). The resulting nascent peptide does not contain the seat belt region (amino acid residues 88-105), a TSH-beta subunit region crucial for the dimerization with the alpha-subunit, and, hence, the correct secretion of the mature TSH heterodimer is hampered. Free T(3), free T(4) as well as basal TSH levels were extremely low in both affected individuals and, importantly, TRH stimulations failed to increase serum TSH, but not PRL, confirming isolated TSH deficiency. Using the new StyI endonuclease restriction site generated by the mutation, we confirmed that the affected children were homozygous for the Q49X TSH-beta mutation whereas their unaffected parents as well as their unaffected brother were heterozygous. Consequently, this isolated TSH deficiency follows an autosomal recessive mode of inheritance.
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PMID:New autosomal recessive mutation of the TSH-beta subunit gene causing central isolated hypothyroidism. 1154 95