Resistance to thyroid hormone and its molecular basis

Area of Science:

• Endocrinology
• Genetics
• Molecular Biology

Background:

• Generalized resistance to thyroid hormone (GRTH) is an inherited syndrome with variable clinical presentations.
• It's often suspected when elevated thyroid hormone levels coexist with non-suppressed thyroid-stimulating hormone (TSH).
• Symptoms range from short stature and learning disabilities in children to goiter in adults, often leading to misdiagnosis.

Purpose of the Study:

• To investigate the genetic basis of Generalized resistance to thyroid hormone (GRTH).
• To understand the mechanism underlying the syndrome's inheritance pattern and clinical heterogeneity.

Main Methods:

• Identification and analysis of mutations in thyroid hormone receptor (TR) genes.
• Correlation of identified mutations with clinical phenotypes and inheritance patterns in affected families.

Main Results:

• Mutations in the TR beta gene were identified in 42 families with GRTH.
• These mutations are located in the T3-binding domain and impair hormone binding.
• Heterozygous subjects with point mutations exhibit GRTH, while complete TR deletion does not, suggesting dominant inheritance mechanisms.

Conclusions:

• Mutations in the TR beta gene are the primary cause of Generalized resistance to thyroid hormone (GRTH).
• The dominant inheritance and heterogeneity of GRTH result from interactions between mutant and normal TR beta, and other factors.
• Understanding the etiology of GRTH enhances diagnostic capabilities and provides insights into thyroid hormone receptor function.