Is my girlfriend's cleft lip hereditary?

In our daily life, we often see many people with upturned, cleft, and incomplete lips. This is called cleft lip, which is also a kind of lip deformity. Cleft lip has certain genetic factors, but not all of them are hereditary. This may be due to gene mutations during pregnancy.

Cleft lip, commonly known as "hare lip", is the most common cleft lip in the oral and maxillofacial region. It is a congenital malformation. Clinically, cleft lip refers to a cleft in the upper lip. Because cleft lip is hereditary, many people are very concerned about the inheritance probability of cleft lip. Is its inheritance probability high? Now let's listen to the professionals' introduction to the specific inheritance probability!

According to medical evidence, cleft lip is mainly caused by abnormal fetal development due to long-term smoking and alcoholism during pregnancy. But to some extent, it may also be caused by polygenic inheritance. Cleft lip is an autosomal recessive gene. It does not cause deformities in every generation, and the chance of inheriting cleft lip is not very high. Only when apparently healthy parents carry this recessive gene, there is a one-fourth chance that their children will have cleft lip. One-half of the children appear healthy but carry this gene, and only one-quarter of the children are healthy. If one of the parents has cleft lip, half of the next generation of children will have cleft lip deformity and the other half will carry the disease-causing gene.

Clinically, the fetus receives one chromosome from each parent, and deformities will only occur when both are recessive genes. Cleft lip is an autosomal recessive inheritance, which does not show deformity in every generation. Only when apparently healthy parents carry the disease-causing gene, will 1/4 of their children develop cleft lip, 1/2 of the children appear healthy but actually carry the disease-causing gene, and only 1/4 of the children are healthy. The incidence of simultaneous occurrence among siblings is 2% to 4%.

If one of the parents carries the disease-causing gene and the other is healthy, then the next generation of children will not have cleft lip, but 1/2 of the children will carry the disease-causing gene. If one parent has cleft lip and the other is healthy, half of the next generation of children will be deformed and the other half will carry the disease-causing gene. If both parents have cleft lip, then the next generation of children will also have cleft lip. There are slightly more males than females with cleft lip, with the male to female ratio being approximately 1.5:1.