Pierre Robin Syndrome

Patient 2 has Pierre Robin Syndrome, which is a disease that results in facial abnormalities. It is inherited in an autosomal recessive fashion. This disease is caused by rearrangements or deletions on the SOX9 gene or the KCNJ2 gene. SOX9 is a transcription factor that turns on other genes involved in skeletal development and embryogenesis. A mutation in this protein is one of the reasons for abnormal ossification. Mutations upstream or downstream of SOX9 can also cause Pierre Robin Syndrome. These mutations produce proteins that are unable to interact with MSX1, a transcription factor that controls formation of structures in the mouth. This causes a fixed jaw and other oral abnormalities characteristic of Pierre Robin Syndrome.