Thyroid dyshormonogenesis 1 (TDH 1) occurs when the thyroid gland does not work correctly and does not make enough thyroid hormone; this condition is a type of hypothyroidism (in which the thyroid does not produce enough thyroid hormone). The thyroid is a gland that has a very important role in regulating growth, brain development, and body metabolism.
TDH 1 is present at birth. While some babies may show no symptoms, others may be less active, sleep more than normal, have difficulty feeding, and experience constipation. If the condition is left untreated, TDH 1 can cause intellectual disability and growth problems. However, if the condition is treated soon after birth, infants should develop normally.
TDH 1 is a genetic condition caused by mutations (changes) in the SLC5A5 gene.We inherit our genes in pairs, one from each parent typically. This condition is inherited in an autosomal recessive manner. Autosomal recessive means that an individual must have two copies of the changed gene or mutation that causes the condition. A person with one changed gene would be a carrier of the condition but usually will not have any symptoms. If both parents are carriers of the condition, each child has a one-in-four chance (25%) of having the disease.
Diagnosis of TDH 1 involves blood tests to check for decreased levels of thyroid hormone. Genetic tests may also be conducted to look for specific changes in the SLC5A5 gene that correlate with TDH 1.
Treatment involves thyroid hormone replacement, specifically the form of levothyroxine. If you or a family member has been diagnosed with Thyroid Dyshormonogenesis 1, talk with your doctor about the most current treatment options. Support groups are also good resources for support and information.
Description Last Updated: Sep 03, 2018