You'll find hundreds of files on cleft lip, cleft palate here on widesmiles.org.
This one is about: The Big Question - What Makes a Cleft?
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THE BIG QUESTION: What Makes a Cleft?
An interesting question came over the widesmiles.org website, and in reading and answering it, I realized that it is, indeed, the question so many of us ask over and over again. Basically, the question was, "What happens?" What happens during fetal development that eventually determines that a child will be born with a cleft of the lip and/or the palate? The question, as I received it was as follows: "I am doing a research paper on cleft palate. I am trying to find info on the development of it. What happens during the fetal stage? Any help would be appreciated."
I considered the question. What happens indeed? Wouldn't we all like to know the answer to that puzzle. Below is the answer I gave the query:
"The actual etiology (cause) of a cleft lip and/or palate is largely unknown, and yet at the same time we know that there are many different things that can contribute to or create a cleft.
The face and facial structures are formed out of three plates, each migrating toward a meeting point in the middle area of the face. The facial structures of the obicularis muscle form the lip. They are joined at the philitrum lines. If you rub your finger above your top lip, you will feel those two ridges. Those are in fact the "cleft scars" of a non cleft-affected person. Those tissues naturally join by the fourth week of pregnancy.
The palate is then formed out of the structure that begins as the tongue and palate. Between the fourth and the eighth weeks of gestation, the tongue drops down and the palatal segments then move from the sides and toward the middle, fusing in the center. Run your tongue across your hard palate from side to side and you will feel the seam where the two sides fused.
A cleft, therefore, is not something that is formed, so much as it is something that does not form. Everyone began life with a cleft. For 699 out of 700 of us, the cleft fuses before birth. For that one in 700, it fails to fuse. So we are not talking about something that happens so much as something that fails to happen.
Why does it fail to happen? Lots of theories, and lots of known reasons. If the tongue, for instance, fails to drop down because the baby is tucked too tightly at that critical time, the result will be a very wide, horseshoe-shaped cleft of the palate. If the blood flow to through the placenta is disrupted at a critical time, the fusion may not occur. Drugs, alcohol or medications may disrupt normal patterns of development. Or some genetic code may simply dictate that it will not happen.
Women who smoke are twice as likely to give birth to a cleft-affected child. Women who ingest large quantities of Vitamin A or low quantities of folic acid are more likely to have children with cleft. A parent with a cleft has a minimum 5% chance of passing the cleft along. A parent with an autosomal dominant genetic condition that results in clefting will have a 50% chance of passing along the condition.
So, as you can see, the answer to your question is very complex, and often unknown. If we knew what happened specifically, perhaps we could avoid it. We all wish life were that simple, but it is not.
Bottom line - what happens when a cleft occurs is that for some
reason or another, the tissues of the lip and/or the palate fail to fuse at the
proper time (4th to 8th weeks of gestation). Why they fail to fuse is a mystery that
scientists are working hard to unravel. And all that we know at this time is, there
is neither a single nor a simple explanation to
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