in this paper, I found some TTSI ( = TT4RI) values of patients with thyroid resistance from a mutation in the THRB gene :
Homozygous Thyroid Hormone Receptor β-Gene Mutations in Resistance to Thyroid Hormone: Three New Cases and Review of the Literature
Conclusion:
We report three new subjects, from two families, in whom RTH was associated with homozygous mutations in the
THRB gene. They represent an important addition to the single known patient homozygous for a mutant TRβ. The clinical and laboratory abnormalities indicate a strong dominant-negative effect and are in agreement with data obtained from mice expressing a mutant
Thrb in both alleles. This report strengthens the concept that the mutated TRβ interferes with the function of the TRα1 in humans.
The syndrome of resistance to thyroid hormone (RTH) is caused by decreased tissue responsiveness to thyroid hormone (TH) (
1,
2). The biochemical hallmark of RTH is abnormally elevated serum free TH levels together with nonsuppressed TSH secretion. The clinical presentation is highly variable, ranging from isolated biochemical abnormalities to a mixture of hypo-hyperthyroid signs and symptoms (
1–
3). The cause is mostly mutations in TH receptor β (
THRB) gene (
1,
2).
With the exception of a single family with recessively inherited RTH due to a deletion of the
THRB gene (
4), inheritance of RTH is autosomal dominant (
1). Clinical and biochemical manifestations are attributed to the interference of mutant TRβ with the function of the normal receptor, a phenomenon termed “dominant-negative effect” (DNE) (
5).
.....
We used the thyrotroph T4 resistance index (TT4RI), the product of FT4I and TSH (
17), to estimate the relative resistance of the hypothalamo-pituitary axis to TH (calculated using data from
Table 3).
This allows the inclusion of individuals on l-T4 replacement. In increasing order of resistance, subjects without WT TRβ from the five families ranked as follows: G<F<Mozv<S<Mbyd, with scores of 920, 4,920, 10,456, 140,290, and 239,120 (normal, 136 ± 73), respectively.
It is of interest that heterozygous relatives ranked in almost similar order F<G<Mozv<S<Mbyd, with scores of 129, 200, 293, 330, and 830, respectively. Note that the TT4RI of heterozygotes of families G and F are well within the normal range.
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