The Norway Facial Clefts Study is a population-based, case-control parent-triad study that explores the environmental and genetic causes of cleft lip and palate. Allen J. Wilcox, M.D., Ph.D., and his research group carried out the study in Norway, where the rate of clefts is one of the highest in the world. During 1996–2001 the group enrolled 88% of babies born in Norway with facial clefts (N = 574) and 78% of a random sample of live births during the same time period (N = 763). Blood was collected from case babies and their biological parents, while cheek swabs were collected from control babies and their parents. Analyses are in progress to explore both genetic and environmental causes of clefts.
Facial clefts are one of the most common types of birth defects, and environmental teratogens have been shown to cause these defects in laboratory animals. Results from human cleft studies conducted by other researchers have indicated strong genetic patterns of clefts with high familial risk, but little evidence for environmental causes. It is plausible that environmental risk factors are harder to detect because they may occur within genetically-susceptible groups.