Scientists discover key to cleft palate

US scientists believe they have discovered what causes cleft palates - one of the most common birth defects.

Cleft palate or cleft lip affects one in 700 newborn Americans.

It is thought to be caused by a combination of genetic and environmental factors.

Previous research has established that abnormalities in the gene that produces Tranforming Growth Factor Alpha (TGF-a) are linked to the defect.

But it was not known how the gene worked.

Docking

The researchers at the University of California have found that, during normal embryonic development, TGF-a docks with a growth factor receptor and produces proteins.

These proteins cause the closure of the palate.

In embryos with cleft palate, TGF-a cannot dock and so the proteins cannot be produced.

The researchers tested their thesis on mice bred without the growth factor receptor.

The results are published in the journal Nature Genetics.

Rik Derynck, professor of cell biology in the Department of Growth and Development at the University of California, said: "This is an intriguing finding because we believe that this animal study will translate very closely to humans."

The research could eventually lead to new therapies to prevent cleft palate.

However, the researchers warn that any progress may be some way off since the majority of cleft palates are thought to be due solely to genetic factors.

Risk factors

Some children are born with both a cleft lip and palate.

A cleft lip can include the bones of the upper jaw and/or the upper gums.

A cleft palate is an opening in the roof of the mouth. The defect is thought to occur very early on in pregnancy.

The risks of the condition being inherited are thought to depend on the number of people affected in the family, the closeness of affected relatives, the race and sex of the people affected and the severity of the clefts.

Boys are thought more likely to develop the condition and Asians, Hispanics and Native Americans are more prone to it than Europeans and Africans.

Smoking, some drugs and pesticides have also been linked to clefting.

Children with cleft palates often require surgery, dental care and speech therapy.