It is a disease that only affects children and is caused by an alteration in a gene on the X chromosome. This pathology entails neurological alterations, causing small delays in the development of intelligence, stiff muscles, and so on.
The first time this disease was described was in the 1940s and it was called Allan-Herndon-Dudley Syndrome , after its discoverers William Allan, Florence C. Dudley and C. Nash Herndon. Later, in 2004, seven years ago, it became known what caused it: a deficiency in a thyroid hormone transporter, the MCT8 transporter, which prevented these substances from reaching the brain in the child’s neural development.
It is a disease that only affects males because it is an alteration of the X chromosome gene. This means that mothers, even being carriers, will never suffer from the disease, but they can transmit the defective gene to their male descendants with a 50 percent chance.
Recently, a group of researchers led by Dr. Juan Bernal, from the Alberto Sols Biomedical Research Institute and the Network Biomedical Research Center for Rare Diseases , have gone one step further to learn more about this disease. According to their study, this hormone deficiency is due to the fact that they cannot cross the blood-brain barrier (BBB) or what is the same, the barrier that protects the brain from harmful substances. And this is due to the defect of their specific transporter, the MCT8. But research has also shown that this defect causes an alteration of thyroid hormones T4 and T3, which has led them to create a clinical guide to diagnose these cases in young children.
The first case in Spain
This system for measuring the hormones T4 and T3 (the first decreases when the MCT8 gene is damaged, while the second increases its presence in the blood) has made it possible to diagnose the first case in Spain with an MCT8 defect.
Although there is no effective treatment to alleviate the effect of this anomaly, its correct diagnosis will serve to genetically advise couples who wish to have children.
