We see such a wide variety of people with clefts including parents and their own children, identical twins with identical clefts, newborns and adults with unrepaired clefts, etc. It is pretty amazing to realize that people's faces are already being shaped at 5-10 weeks gestation, sometimes when mothers-to-be do not realize they are even pregnant.
No one knows what causes clefts, but many believe there are a combination of causes, plus a genetic pre-disposition and environmental issues. The environmental risks include substances like drugs and alcohol, smoking (personal and passive), maternal illness, infections, and lack of vitamin B folic acid. Clefts are noted to occur more often in mothers who are younger than 18 and older than 35.
Also, exposure to "teratogens"* - medications, chemicals, infectious diseases, and environmental agents - can interfere with the normal development of a fetus. They include alcohol, cocaine, cigarettes, seizure medications, accutane, chemotherapy, radiation, lithium, organic solvents, lead, anesthetic gases, and mercury. Diseases that could impact a developing fetus include measles, herpes, diabetes, and anything that causes a high fever, for example. Many expectant mothers (~70%), especially in Vietnam, tend to be anemic throughout their pregnancies. That condition alone jeopardizes the overall health of the mother and child. Protein-deficient anemias and general malnutrition from lacking nutrients are a regular challenge for overall maternal and infant well-being.
Cleft deformities can also present with other genetic issues/syndromes. About one-sixth of all babies born with clefts have other conditions, so they need a complete physical examination when a cleft is noted.
Much can be done to help these people born with clefts and minimize the deformity and scarring. The majority of people born with clefts may be completely normal in most or all other regards.
A teratogen is any agent that interferes with the development of an embryo or fetus, maybe causing a birth defect or even the death of a fetus. If one explores teratogens further, one would find lists of well over 400 different agents so far known to cause damage.
We continue to monitor to some extent the regions from where the patients with cleft and other congenital deformities call home. One of the most toxic known teratogens is 2,3,7,8-tetrachlorodibenzodioxin (TCDD, or dioxin, or Agent Orange). Regions in Vietnam where the highest reported incidences of deformities are in southern and south-central coastal Vietnam. They tend to correlate with populations near mangrove forests and sites where food crops were exposed to TCDD.
The greatest incidences of which we are aware are from Bien Hoa (20 miles from Saigon) in Dong Nai Province, Phu Cat, in south-central coastal Binh Dinh Province, and Da Nang, along with Hue (the Imperial City) and Hoi An, near the mouth of the Han River and South China Sea. In a like fashion, an increase in solid tumors, blood and lymph cancers, and endocrine disorders, like diabetes, are all now also being analyzed for these regions.