A new genetic test could allow doctors to identify people at risk of having a second child with a cleft lip or palate. Researchers at the University of Iowa in the US found that variations in a particular gene are linked to a three-fold increased risk of the condition recurring, in families that already have one affected child. The researchers say their study, published in the New England Journal of Medicine will make it possible to determine whether the risk of a second affected child is 'one or 20 per cent'.
Cleft lip or palate (or the two together) is a common birth defect, caused by a mixture of genetic and environmental factors. It results in a failure of the tissues of the upper jaw, lip or roof of the mouth to join properly, and can usually be corrected surgically. To search for genes involved in the condition, the scientists studied 1968 families from ten different Asian, European and South American populations. They looked at a particular variation in a gene called IRF6, which makes a protein called interferon regulatory factor 6. Mutations in this gene are known to cause a purely genetic form of cleft lip and palate, called Van der Woude's syndrome.
The researchers found that the IRF6 gene variation increased the risk of recurrence in families that already had one child born with a cleft lip, or cleft lip and palate, from three per cent to nine per cent. In a commentary accompanying the article, Aravinda Chakravati, of the Johns Hopkins School of Medicine, says that such families would require careful genetic counselling with regard to diagnosis, patient care and treatment options. She adds: 'However, it is unlikely that families would react very differently to a recurrence of 3 to 5 per cent that to a risk of 9 per cent'.
Team leader Jeffrey Murray said that knowing about the presence of a cleft lip before the birth of a child could help parents prepare for it, both emotionally and in terms of medical care. The findings also pave the way for further research into the condition, to help untangle the role of genes and environmental factors such as maternal exposure to tobacco smoke.