Research offers insight into how identical twins occur

An international group of researchers has made a discovery that could lead to new insights into how identical twins occur.        

Their study was led by Dr Jenny van Dongen and Professor Dorret Boomsma of the Vrije Universiteit in Amsterdam, and involved scientists from QIMR Berghofer.

The researchers studied several large twin cohorts in the Netherlands, Australia, the United Kingdom and Finland to find if identical twins – share a unique epigenetic profile.

The head of the Genetic Epidemiology Research Group at QIMR Berghofer, Professor Nick Martin, who led the Australian team, said it was an exciting breakthrough.

“Over the past 100 years, we’ve made huge advances on most of the big puzzles in biology but the origins of identical twins remain a mystery,” Professor Martin said.

The researchers found identical twins have a unique epigenetic profile when they measured methylation in the DNA of thousands of identical twins and compared it to non-identical twins. DNA methylation is a process controlling gene expression – which genes are switched “on” and “off” in each cell of the body.

The study revealed there were 834 DNA locations where the methylation level was the same for identical twins, which differs to non-twins. 

“These locations in the DNA are involved in functions in early embryonic development,” said Dr Jenny van Dongen, who led the study. 

Identical twins are formed when a single fertilised egg splits and develops into two babies.

“In addition to insights into the origins of identical twins, our results may lead to a better understanding of congenital abnormalities that occur more often in identical twins in the future,” Professor Martin said.

Insights into early development of identical twins and genetic conditions like spina bifida that commonly occur in identical twins, might provide a way to do something about them. This research is a major step forward.

John Lee, a 44-year-old identical twin from Brisbane and his wife Sommer, are hopeful that the research could lead to better health outcomes for identical twins.

“John and his brother Gene were both diagnosed with Graves’ disease in their teens and had their thyroids removed. Gene got sick and was diagnosed, so then John was tested
before he developed symptoms and he also had the disease.”

“Over the years, I’ve learned so much about identical twins, but it would be good to understand more about medical issues that might be unique to them,” said Sommer



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