There is no known cause for this defect. It is not a genetic disorder in the true sense, but if one child is affected, then the possibility of the subsequent child having the defect is slightly higher than in the normal population. There is no way to know about the defect before the baby is born. However, if there is associated cleft lip, it may be possible to identify it by a good pre-natal ultrasound scan. There are several centres that do this work. In all major cities there are paediatric surgeons and plastic surgeons who perform these operations.