Question: What causes Hemifacial microsomia ?
Answer: What causes hemifacial microsomia? For most people with hemifacial microsomia, the cause is unknown. It is believed that something occurs in the early stages of development, such as a disturbance of the blood supply to the first and second branchial arches in the first 6 to 8 weeks of pregnancy. Studies have suggested multiple possible risk factors for hemifacial microsomia. Environmental risk factors include the use of medications during pregnancy such as Accutane, pseudoephedrine, aspirin, or ibuprofen. Other environmental factors include second trimester bleeding, maternal diabetes, being pregnant with multiples, or the use of assisted reproductive technology. A genetic cause is found in some families, such as a chromosome disorder or a genetic syndrome. Some possible explanations when the cause of hemifacial microsomia is unknown include a very small chromosome deletion or duplication that is not detected, a mutation in an unknown gene, or changes in multiple genes associated with development of the face. It is also possible that a combination of genetic changes and environmental risk factors could cause hemifacial microsomia.
Source: GARD