Among the known human congenital malformations, about 10% is directly caused by chromosome abnormality or single gene transmission room, 10% is directly caused by environmental factors, and the remaining 80% is the result of the joint action of genetic and environmental teratogenic factors, especially people with polygenic genetic basis are more susceptible to environmental factors.
Extended data:
Formation stage of the brain base: The above five pairs of cartilage (except the cartilage of the eye) surround the back of the eyeball and do not participate in the formation of the skull. After the other four pairs of cartilage heal, they form a cartilage groove to support the ventral surface of the brain, and the two sides slightly surround the brain and extend to the back of the brain to form a cartilage cover.
The soft skull thus formed has no top, only at the cartilage covering, and the two sides are connected at the top. Add posterior membranous bone and cover the back to form a complete skull.
Baidu Encyclopedia-Craniofacial Bone Malformation Syndrome