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Reviewed May 2006
What is congenital hypothyroidism?
Congenital hypothyroidism is a condition that affects infants from birth (congenital) and results from a partial or complete loss of thyroid function (hypothyroidism). The thyroid gland is a butterfly-shaped tissue in the lower neck. It makes iodine-containing hormones that play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism).
Congenital hypothyroidism occurs when the thyroid gland fails to develop or function properly. In 80 to 85 percent of cases, the thyroid gland is absent, abnormally located, or severely reduced in size (hypoplastic). In the remaining cases, a normal-sized or enlarged thyroid gland is present, but production of thyroid hormones is decreased or absent. If untreated, congenital hypothyroidism can lead to intellectual disability and abnormal growth. In the United States and many other countries, all newborns are tested for congenital hypothyroidism. If treatment begins in the first month after birth, infants usually develop normally.
How common is congenital hypothyroidism?
Studies of populations from North America, Europe, Japan, and Australia, indicate that congenital hypothyroidism affects 1 in 3,000 to 4,000 newborns. For reasons that remain unclear, congenital hypothyroidism affects more than twice as many females as males.
What genes are related to congenital hypothyroidism?
Mutations in the DUOX2, PAX8, SLC5A5, TG, TPO, TSHB, and TSHR genes cause congenital hypothyroidism.
Gene mutations cause the loss of thyroid function in one of two ways. Mutations in the PAX8 gene and some mutations in the TSHR gene prevent or disrupt the normal development of the thyroid gland before birth. Mutations in the DUOX2, SLC5A5, TG, TPO, and TSHB genes prevent or reduce the production of thyroid hormones, even though the thyroid gland is present.
Mutations in other genes that have not been well characterized may also cause congenital hypothyroidism.
How do people inherit congenital hypothyroidism?
Most cases of congenital hypothyroidism are sporadic, which means they occur in people with no history of the disorder in their family.
An estimated 15 to 20 percent of cases are inherited. Many inherited cases are autosomal recessive, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.
Some inherited cases (those with a mutation in the PAX8 gene or certain TSHR gene mutations) have an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
Where can I find information about diagnosis or management of congenital hypothyroidism?
These resources address the diagnosis or management of congenital hypothyroidism and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about congenital hypothyroidism?
You may find the following resources about congenital hypothyroidism helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for congenital hypothyroidism?
What if I still have specific questions about congenital hypothyroidism?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding congenital hypothyroidism?
autosomal ; autosomal dominant ; autosomal recessive ; cell ; congenital ; dysgenesis ; gene ; hypothyroidism ; inheritance ; iodine ; metabolism ; mutation ; newborn screening ; pattern of inheritance ; recessive ; screening ; sporadic ; thyroid ; thyroid hormones ; tissue
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (10 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.