S'pore scientist find mutation responsible for rare birth defect

Photo above: (Left) Full facial photograph of individual with Hamamy Syndrome. (Right) Long bone fracture of individual with Hamamy syndrome.

SINGAPORE - Scientists at A*STAR's Institute of Medical Biology (IMB) have identified the genetic cause of a birth defect known as Hamamy syndrome.

Hamamy syndrome is a rare genetic disorder which is marked by abnormal facial features and defects in the heart, bone, blood and reproductive cells.

Only a handful of people in the world have been identified with Hamamy Syndrome making it a very rare genetic disorder.

Its exact cause was unknown until the groundbreaking discovery, which was done in collaboration with with doctors and scientists in Jordan, Turkey, Switzerland and USA.

The international team have pinpointed the genetic mistake to be a mutation in a single gene called IRX5.

IRX5 is part of a family of transcription factors that is highly conserved in all animals, meaning that this gene is present not only in humans but also in mice, fish, frogs, flies and even worms.

Using a frog model, the scientists demonstrated that Irx5 orchestrates cell movements in the developing foetus which underlie head and gonad formation.

The work lends new insights into common ailments such as heart disease, osteoporosis, blood disorders and possibly sterility.

The findings also provide a framework for understanding evolutionary questions, such as why humans of different ethnicities have distinct facial features and how these are embedded in our genome, said Dr Bruno Reversade, Senior Principle Investigator at IMB.

This is as IRX genes have been repeatedly co-opted during evolution, and small variations in their activity could underlie differences in an organism's appearance.

Rare genetic diseases, usually caused by mutations in a single gene, provide a unique opportunity to better understand more common disease processes.

These "natural" experiments are similar to carefully controlled knockout animal experiments, in which the function of single genes are analysed and often give major insights into general health issues, the researchers said.

yamadak@sph.com.sg