| Etiology | Incidence |
| Genetic | 15-25% |
| Chromosomal | 10-15% |
| Single Gene | 2-10% |
| Multifactorial | 20-25% |
| Environmental | 8-12% |
| Maternal Disease | 6-8% |
| Uterine/Placental | 2-3% |
| Drugs/Chemical | 0.5-1% |
| Twinning | 0.5-1% |
| Unknown | 40-60% |
Stevenson, R. 1993. Human Malformation
and Related Anomalies.
| Genetics |
| Net Scut Home |
