Study shows DNA may affect thyroid hormone levels

According to new research, sequence variations in DNA have been identified that affect levels of thyroid hormones.

A research team from the University of Western Australia's School of Medicine and Pharmacology carried out a study of 2,031 female twins and identified the most common DNA variants in their genes. To confirm their findings, they then tested 1,154 people from the Busselton Health Study in Western Australia. The results were published in The American Journal of Human Genetics.

Associate professor John Walsh said evaluation of thyroid function was generally performed by measuring circulating concentrations of thyroid-related hormones.

"Thyrotropin (also known as TSH) is the most sensitive marker of thyroid dysfunction," Walsh said. "Even in healthy subjects, there can be considerable differences in hormone levels between different people in the population, but the levels are generally tightly regulated within an individual person over time."

He added that this suggests that individuals have different setpoints for thyroid hormones, which research has shown are under strong genetic control.

Adjunct associate professor Scott Wilson said that since genetic variations were present in more than one in four people examined, there may be a potential role for screening as part of a wider program of personalised genomic medicine.