Pierre Robin nonsyndromic or isolated (Isolated Pierre Robin sequence) - Gen SOX9  

Pierre Robin sequence or Pierre Robin syndrome, is a set of conditions affecting the head and face, and consisting micrognatia, glossoptosis, obstruction of the airways and palate. This disease is described as a "sequence", because of its characteristics, an underdeveloped lower jaw, initiates a sequence of events before birth resulting in the other signs and symptoms. Specifically, an abnormally small jaw affects the placement of the tongue and palate formation, leading to glossoptosis and palate.

The combination of the characteristics of Pierre Robin sequence can cause respiratory distress and trouble eating early in life. Consequently, some affected newborns are stunted. In some affected children, the defect of the jaw is corrected over time and get to have chins normal size. Some people have Pierre Robin sequence as part of a syndrome that affects other organs and tissues in the body, such as campomelic dysplasia or Stickler syndrome. They are described as syndromic. When Pierre Robin sequence occurs by itself, it described as non - syndromic or isolated. Approximately 20 to 40% of cases of Pierre Robin sequence are isolated.

Changes in the DNA near the gene SOX9 (SRY-box 9) are the most common genetic cause of isolated Pierre Robin sequence. This gene, located on the long arm of chromosome 17 (17q24.3), encodes a protein that plays a critical role in the formation of many different tissues and organs during embryonic development. The SOX9 protein is especially important for skeletal development and plays a key role in determining sex before birth. Protein, regulates the activity of other genes, especially those that are important in skeletal development and reproductive organs.

It is believed that genetic changes associated with Pierre Robin sequence interrupted regions normally govern gene SOX9 during development of the lower jaw, which reduces the activity of the gene SOX9. Consequently, SOX9 protein can not adequately control the genes essential for the normal development of the mandible, resulting micrognatia. Underdevelopment of the lower jaw affects the placement of the tongue and palate formation, leading to glossoptosis and palate.

It is likely that changes in other genes, some of which have not been identified, are also involved in the development of this process. It is believed that certain non - genetic factors, for example during pregnancy conditions that restrict growth of the mandible may be responsible for some isolated cases of the disease.

Pierre Robin sequence usually not inherited, but is due to new genetic changes it occurs in people with no history of disease in your family. When the disease is inherited, is an autosomal dominant, which means that a copy of the altered DNA in each cell is sufficient to express the alteration.  

Tests in IVAMI: in IVAMI perform detection of mutations associated with Pierre Robin sequence, by complete PCR amplification of exons in the gene SOX9 and subsequent sequencing.


Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).