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, and seizures. Some affected individuals have thyroid problems, such as an enlargement of the thyroid gland, known as multinodular goiter, or a condition called Hashimoto thyroiditis. 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.

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.

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.

Genetic Testing Information

• Genetic Testing Registry: Bannayan-Riley-Ruvalcaba syndrome

Genetic and Rare Diseases Information Center

• Bannayan-Riley-Ruvalcaba syndrome

Patient Support and Advocacy Resources

• National Organization for Rare Disorders (NORD)

Clinical Trials

• ClinicalTrials.gov

Catalog of Genes and Diseases from OMIM

• COWDEN SYNDROME 1; CWS1

Scientific Articles on PubMed

• PubMed

• Blumenthal GM, Dennis PA. PTEN hamartoma tumor syndromes. Eur J Hum Genet. 2008 Nov;16(11):1289-300. doi: 10.1038/ejhg.2008.162. Epub 2008 Sep 10. Citation on PubMed
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• Hobert JA, Eng C. PTEN hamartoma tumor syndrome: an overview. Genet Med. 2009 Oct;11(10):687-94. doi: 10.1097/GIM.0b013e3181ac9aea. Citation on PubMed
• Lynch NE, Lynch SA, McMenamin J, Webb D. Bannayan-Riley-Ruvalcaba syndrome: a cause of extreme macrocephaly and neurodevelopmental delay. Arch Dis Child. 2009 Jul;94(7):553-4. doi: 10.1136/adc.2008.155663. Epub 2009 Mar 25. Citation on PubMed
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• Marsh DJ, Kum JB, Lunetta KL, Bennett MJ, Gorlin RJ, Ahmed SF, Bodurtha J, Crowe C, Curtis MA, Dasouki M, Dunn T, Feit H, Geraghty MT, Graham JM Jr, Hodgson SV, Hunter A, Korf BR, Manchester D, Miesfeldt S, Murday VA, Nathanson KL, Parisi M, Pober B, Romano C, Eng C, et al. PTEN mutation spectrum and genotype-phenotype correlations in Bannayan-Riley-Ruvalcaba syndrome suggest a single entity with Cowden syndrome. Hum Mol Genet. 1999 Aug;8(8):1461-72. doi: 10.1093/hmg/8.8.1461. Citation on PubMed
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• Zbuk KM, Eng C. Cancer phenomics: RET and PTEN as illustrative models. Nat Rev Cancer. 2007 Jan;7(1):35-45. doi: 10.1038/nrc2037. Epub 2006 Dec 14. Citation on PubMed
• Zhou XP, Waite KA, Pilarski R, Hampel H, Fernandez MJ, Bos C, Dasouki M, Feldman GL, Greenberg LA, Ivanovich J, Matloff E, Patterson A, Pierpont ME, Russo D, Nassif NT, Eng C. Germline PTEN promoter mutations and deletions in Cowden/Bannayan-Riley-Ruvalcaba syndrome result in aberrant PTEN protein and dysregulation of the phosphoinositol-3-kinase/Akt pathway. Am J Hum Genet. 2003 Aug;73(2):404-11. doi: 10.1086/377109. Epub 2003 Jul 3. Citation on PubMed or Free article on PubMed Central