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Reviewed September 2012
What is Bannayan-Riley-Ruvalcaba syndrome?
Bannayan-Riley-Ruvalcaba syndrome is a genetic condition characterized by a large head size (macrocephaly), multiple noncancerous tumors and tumor-like growths called hamartomas, and dark freckles on the penis in males. The signs and symptoms of Bannayan-Riley-Ruvalcaba syndrome are present from birth or become apparent in early childhood.
At least half of affected infants have macrocephaly, and many also have a high birth weight and a large body size (macrosomia). Growth usually slows during childhood, so affected adults are of normal height and body size. About half of all children with Bannayan-Riley-Ruvalcaba syndrome have intellectual disability or delayed development, particularly the development of speech and of motor skills such as sitting, crawling, and walking. These delays may improve with age.
About half of all people with Bannayan-Riley-Ruvalcaba syndrome develop hamartomas in their intestines, known as hamartomatous polyps. Other noncancerous growths often associated with Bannayan-Riley-Ruvalcaba syndrome include fatty tumors called lipomas and angiolipomas that develop under the skin. Some affected individuals also develop hemangiomas, which are red or purplish growths that consist of tangles of abnormal blood vessels. People with Bannayan-Riley-Ruvalcaba syndrome may also have an increased risk of developing certain cancers, although researchers are still working to determine the cancer risks associated with this condition.
Other signs and symptoms that have been reported in people with Bannayan-Riley-Ruvalcaba syndrome include weak muscle tone (hypotonia) and other muscle abnormalities, thyroid problems, and seizures. Skeletal abnormalities have also been described with this condition, including an unusually large range of joint movement (hyperextensibility), abnormal side-to-side curvature of the spine (scoliosis), and a sunken chest (pectus excavatum).
The features of Bannayan-Riley-Ruvalcaba syndrome overlap with those of another disorder called Cowden syndrome. People with Cowden syndrome develop hamartomas and other noncancerous growths; they also have an increased risk of developing certain types of cancer. Both conditions can be caused by mutations in the PTEN gene. Some people with Bannayan-Riley-Ruvalcaba syndrome have had relatives diagnosed with Cowden syndrome, and other individuals have had the characteristic features of both conditions. Based on these similarities, researchers have proposed that Bannayan-Riley-Ruvalcaba syndrome and Cowden syndrome represent a spectrum of overlapping features known as PTEN hamartoma tumor syndrome instead of two distinct conditions.
Read more about Cowden syndrome.
How common is Bannayan-Riley-Ruvalcaba syndrome?
The prevalence of Bannayan-Riley-Ruvalcaba syndrome is unknown, although it appears to be rare. Several dozen cases have been reported in the medical literature. Researchers suspect that the disorder is underdiagnosed because its signs and symptoms vary and some of them are subtle.
What genes are related to Bannayan-Riley-Ruvalcaba syndrome?
About 60 percent of all cases of Bannayan-Riley-Ruvalcaba syndrome result from mutations in the PTEN gene. Another 10 percent of cases are caused by a large deletion of genetic material that includes part or all of this gene. The protein produced from the PTEN gene is a tumor suppressor, which means that it normally prevents cells from growing and dividing (proliferating) too rapidly or in an uncontrolled way. If this protein is missing or defective, cell proliferation is not regulated effectively. Uncontrolled cell division can lead to the formation of hamartomas and other cancerous and noncancerous tumors. The protein produced from the PTEN gene likely has other important functions within cells; however, it is unclear how mutations in this gene can cause the other features of Bannayan-Riley-Ruvalcaba syndrome, such as macrocephaly, developmental delay, and muscle and skeletal abnormalities.
When Bannayan-Riley-Ruvalcaba syndrome is not caused by mutations or deletions of the PTEN gene, the cause of the condition is unknown.
Read more about the PTEN gene.
How do people inherit Bannayan-Riley-Ruvalcaba syndrome?
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
In some cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.
Where can I find information about diagnosis or management of Bannayan-Riley-Ruvalcaba syndrome?
These resources address the diagnosis or management of Bannayan-Riley-Ruvalcaba syndrome and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about Bannayan-Riley-Ruvalcaba syndrome?
You may find the following resources about Bannayan-Riley-Ruvalcaba syndrome helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for Bannayan-Riley-Ruvalcaba syndrome?
What if I still have specific questions about Bannayan-Riley-Ruvalcaba syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding Bannayan-Riley-Ruvalcaba syndrome?
autosomal ; autosomal dominant ; cancer ; cell ; cell division ; cell proliferation ; deletion ; developmental delay ; disability ; gene ; hamartoma ; hamartomatous ; hypotonia ; inherited ; joint ; macrocephaly ; motor ; muscle tone ; mutation ; pectus excavatum ; prevalence ; proliferating ; proliferation ; protein ; scoliosis ; spectrum ; syndrome ; thyroid ; tumor
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (10 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.