Central hypothyroidism

Area of Science:

• Pediatric Endocrinology
• Human Genetics
• Molecular Biology

Background:

• Congenital hypothyroidism (CH) is a common endocrine disorder in newborns, requiring timely diagnosis and treatment to prevent developmental issues.
• Genetic factors play a significant role in the etiology of CH, with mutations in various genes implicated.

Observation:

• A 15-month-old male child from a consanguineous family presented with classic symptoms of congenital hypothyroidism.
• Biochemical tests revealed low serum levels of thyroxine (T4) and triiodothyronine (T3), along with suppressed thyroid-stimulating hormone (TSH).
• Pituitary imaging via magnetic resonance imaging (MRI) showed normal results, ruling out other pituitary hormone deficiencies.

Findings:

• Genetic analysis identified a homozygous missense mutation in the TSHB gene, specifically a G to A single base substitution at codon 85.
• This mutation leads to an amino acid change from Glycine to Arginine at position 85 in the TSH beta subunit.
• The identified TSHB gene mutation has been previously documented in three other patients with a similar clinical presentation.

Implications:

• This case reinforces the TSHB gene as a critical determinant of thyroid hormone synthesis and secretion.
• The findings highlight the importance of genetic testing in diagnosing congenital hypothyroidism, particularly in cases with consanguineous parents.
• Understanding the molecular basis of CH aids in genetic counseling and potentially in developing targeted therapeutic strategies.