By Tengku Noor Shamsiah Tengku Abdullah

SINGAPORE, May 14 (Bernama) -- Scientists at A*STAR's Institute of Medical Biology (IMB), in collaboration with doctors and scientists in Jordan, Turkey, Switzerland and USA, have identified the genetic cause of a birth defect known as Hamamy syndrome.

Their groundbreaking findings were published yesterday in the prestigious journal Nature Genetics. The work lends new insight into common ailments such as heart disease, osteoporosis, blood disorders and possibly sterility.

Hamamy syndrome is a rare genetic disorder which is marked by abnormal facial features and defects in the heart, bone, blood and reproductive cells but its exact cause was unknown until now.

The international team, led by scientists at IMB, have pinpointed the genetic mistake to be a mutation in a single gene called IRX5.

This is the first time that a mutation in IRX5 (and the family of IRX genes) has ever been discovered in man.

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.

Carine Bonnard, a final-year PhD student at IMB and the first author of the paper, said, "Because Hamamy syndrome causes a wide range of symptoms, not just in newborn babies but also in the adult, this implies that IRX5 is critical for development in the womb as well as for the function of many organs in our adult body.

For example, patients with this disease cannot evacuate tears from their eyes, and they will also go on to experience repetitive bone fractures or progressive myopia as they age.

This discovery of the causative gene is a significant finding that will catalyze research efforts into the role of the Irx gene family and greatly increase our understanding of human health, such as bone homeostasis, or gamete formation for instance."

Dr Bruno Reversade, Senior Principle Investigator at IMB said: "We believe that this discovery could open up new therapeutic solutions to common diseases like osteoporosis, heart disease, anemia which affect millions of people worldwide.

He said the findings also provide a framework for understanding fascinating evolutionary questions, such as why humans of different ethnicities have distinct facial features and how these are embedded in our genome.

-- BERNAMA