Bannayan-Riley-Ruvalcaba syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

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.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

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.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

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.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

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.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal large intestine morphology · Very frequent (99-80%)

Any abnormality of the large intestine.

Arteriovenous malformation · Very frequent (99-80%)

An anomalous configuration of blood vessels that shunts arterial blood directly into veins without passing through the capillaries.

Capillary hemangioma · Very frequent (99-80%)

The presence of a capillary hemangioma, which are hemangiomas with small endothelial spaces.

Hamartomatous polyposis · Very frequent (99-80%)

Polyp-like protrusions which are histologically hamartomas. These can occur throughout the gastrointestinal tract. Hamartomatous polyps are composed of the normal cellular elements of the gastrointestinal tract, but have a markedly distorted architecture.

Intestinal polyposis · Very frequent (99-80%)

The presence of multiple polyps in the intestine.

Lipoma · Very frequent (99-80%)

Benign neoplasia derived from lipoblasts or lipocytes of white or brown fat. May be angiomatous or hibernomatous.

Macrocephaly · Very frequent (99-80%)

Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.

Neoplasm of the breast · Very frequent (99-80%)

A tumor (abnormal growth of tissue) of the breast.

Other findings in the same source

From: Orphanet

Additional reported features include Nevus (Very frequent (99-80%)); Short stature (Very frequent (99-80%)); Irregular hyperpigmentation (Very frequent (99-80%)); Visceral angiomatosis (Very frequent (99-80%)); Pectus excavatum (Frequent (79-30%)); Scoliosis (Frequent (79-30%)); Subcutaneous hemorrhage (Frequent (79-30%)); Subcutaneous nodule (Frequent (79-30%)); Abdominal wall muscle weakness (Occasional (29-5%)); Abnormal optic nerve morphology (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Bannayan-Riley-Ruvalcaba syndrome is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Bannayan-Riley-Ruvalcaba syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.