Читать книгу The Healthy Thyroid: What you can do to prevent and alleviate thyroid imbalance - Patsy Westcott - Страница 37

The tendency for autoimmune diseases to run in families provides one clue. It suggests that a faulty gene or genes may be partly to blame. Indeed, scientists have identified a handful of so-called ‘susceptibility’ genes that render some of us more vulnerable to autoimmune attack. They have also pinpointed several areas – ‘susceptibility regions’ – on chromosomes, the 23 pairs of rod-like structures that carry our genes, that appear to confer a greater risk of autoimmunity.

Many autoimmune diseases, including autoimmune thyroid disease, are strongly associated with a gene for human leukocyte antigens (HLA) found on chromosome 6. Another susceptibility gene, CTLA-4 (cytotoxic T lymphocyte-4), is also involved. Both these genes are known as immune-modifying genes – they alter the way in which your immune system behaves. As well as susceptibility genes, researchers are also finding genes that are specifically involved in autoimmune thyroid problems. These ‘thyroid-specific genes’ are thought to work hand-in-hand with susceptibility genes to trigger an autoimmune attack against the thyroid.

As to why women are at greater risk than men, scientists have come up with an intriguing theory that suggests that it may be connected with the continued presence of foreign cells from a fetus in the mother’s bloodstream – and vice versa. Another way to acquire cells that aren’t your own is from a twin, even one you didn’t know you had, because it is now known that a number of pregnancies start out as twin pregnancies, but soon lose one of the embryos. Says Dr J. Lee Nelson, the American scientist who pioneered this theory, ‘Our concept of self has to be modified a little bit. We’re not as completely self as we thought we were.’