When the researchers looked at the gene and nearby regions of the chromosome, they identified a total of 36 DNA variations, nine of which seemed to be associated with clefting. The individual variations were then assembled into a collective profile called a "haplotype." "What we found is that a particular haplotype is over-transmitted in some families with isolated clefts, suggesting a predictive association with the birth defect, and this was true in the populations that we analyzed from The Philippines, Denmark, and the United States."
Based on a detailed analysis of 1,316 families, the scientists estimated that the risk of parents with this haplotype having a second child with isolated cleft lip and palate is about 12 percent. As the researchers noted, their estimate is based on their analysis of the families and cannot be generalized to the broader public.
"For a complex trait like cleft lip and palate, this is a nice step forward because there may be dozens of genes that contribute to the condition," said Murray.
Contact: John Peterson
NIH/National Institute of Environmental Health Sciences