July 2002 -- Dutch researchers have discovered a new cause of congenital hypothyroidism. Previously, it was known that there are a variety of genetic defects that cause cause permanent congenital hypothyroidism – hypothyroidism from birth. And transient congenital hypothyroidism, which resolves within a few months after birth, can be caused by immunologic, environmental, and other external factors, but hasnever before been attributed to any genetic defect.
According to researchers at the University of Amsterdam in the Netherlands, however, a molecular defect in what’s known as the thyroid oxidase system may be involved in both permanent and transient congenital hypothyroidism. This defect was discovered in four of nine patients who had unexplained congenital hypothyroidism.
The study’s lead author Dr. Jose C. Moreno of told Reuters Health, "We have found a new cause of congenital hypothyroidism."
The researchers found that a child who had a severe case of hypothyroidism had inherited 2 mutated genes thyroid oxidase 2 (THOX2) genes. These are the genes that help produce thyroid hormone. Several other children in the study who had milder, transient forms of hypothyroidism carried one mutated and one normal THOX2 gene.
This is the first time that a genetic cause has been found for transient congenital hypothyroidism. It is also of interest because even though transient hypothyroidism resolves itself within months after birth, the genetic defect remains, and some people may again become hypothyroid during periods when the body has a higher need for thyroid hormone—such as during pregnancy. So identifying those people who carry the transient form of the genetic defect may also allow for closer monitoring of people who face a risk of recurrent hypothyroidism later in life.
The study was published in the July 11, 2002 issue of The New England Journal of Medicine.
SOURCE: The New England Journal of Medicine, 2002;347:95-102.