Rubinstein-Taybi syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Rubinstein-Taybi syndrome is a condition characterized by short stature, moderate to severe intellectual disability, distinctive facial features, and broad thumbs and first toes. Additional features of the disorder can include eye abnormalities, heart and kidney defects, dental problems, and obesity. These signs and symptoms vary among affected individuals. People with this condition have an increased risk of developing particular types of noncancerous brain and skin tumors.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the CREBBP gene cause about half of cases of Rubinstein-Taybi syndrome. The CREBBP gene provides instructions for making a protein that helps control the activity of many other genes. This protein, called CREB binding protein, plays an important role in regulating cell growth and division and is essential for normal development before birth. Because one copy of the CREBBP gene is deleted or mutated in people with Rubinstein-Taybi syndrome, their cells make only half of the normal amount of CREB binding protein. A reduction in the amount of this protein disrupts normal development before and after birth. Abnormal brain development is thought to underlie intellectual disability in people with Rubinstein-Taybi syndrome. Researchers have not determined how CREBBP gene mutations lead to other signs and symptoms of Rubinstein-Taybi syndrome.

Mutations in the EP300 gene cause a small percentage of cases of Rubinstein-Taybi syndrome. Like the CREBBP gene, this gene provides instructions for making a protein that helps control the activity of other genes. It also appears to be important for development before and after birth. EP300 gene mutations result in the loss of one functional copy of the gene in each cell, which interferes with normal development and causes the typical features of Rubinstein-Taybi syndrome. The signs and symptoms of this disorder caused by EP300 gene mutations are typically milder than those caused by mutations in the CREBBP gene.

Several cases of severe Rubinstein-Taybi syndrome have resulted from a deletion of genetic material from the short (p) arm of chromosome 16. Multiple genes, including the CREBBP gene, are missing as a result of this deletion. Researchers believe that the loss of multiple genes in this region probably accounts for the serious complications associated with severe Rubinstein-Taybi syndrome. Some researchers suggest that these cases are a separate condition called chromosome 16p13.3 deletion syndrome. However, a few studies indicate that some people with large deletions in the same region of chromosome 16 have characteristic features of Rubinstein-Taybi syndrome rather than a more severe condition.

Nearly 30 to 40 percent of people with Rubinstein-Taybi syndrome do not have an identified mutation in the CREBBP or EP300 gene or a chromosome 16 deletion. The cause of the condition is unknown in these cases. Researchers predict that mutations in other genes can also cause the disorder.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is considered to have an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Rubinstein-Taybi syndrome is uncommon; it occurs in an estimated 1 in 100,000 to 125,000 newborns.

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.

Brachydactyly · Very frequent (99-80%)

Digits that appear disproportionately short compared to the hand/foot. The word brachydactyly is used here to describe a series distinct patterns of shortened digits (brachydactyly types A-E). This is the sense used here.

Broad hallux phalanx · Very frequent (99-80%)

An increase in width in one or more phalanges of the big toe.

Broad thumb · Very frequent (99-80%)

Increased thumb width without increased dorso-ventral dimension.

Convex nasal ridge · Very frequent (99-80%)

Nasal ridge curving anteriorly to an imaginary line that connects the nasal root and tip. The nose appears often also prominent, and the columella low.

Delayed speech and language development · Very frequent (99-80%)

A degree of language development that is significantly below the norm for a child of a specified age.

Downslanted palpebral fissures · Very frequent (99-80%)

The palpebral fissure inclination is more than two standard deviations below the mean.

Feeding difficulties in infancy · Very frequent (99-80%)

Impaired feeding performance of an infant as manifested by difficulties such as weak and ineffective sucking, brief bursts of sucking, and falling asleep during sucking. There may be difficulties with chewing or maintaining attention.

Global developmental delay · Very frequent (99-80%)

A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.

Other findings in the same source

From: Orphanet

Additional reported features include High palate (Very frequent (99-80%)); Hypertelorism (Very frequent (99-80%)); Intellectual disability (Very frequent (99-80%)); Joint hypermobility (Very frequent (99-80%)); Low-set ears (Very frequent (99-80%)); Short stature (Very frequent (99-80%)); Talon cusp (Very frequent (99-80%)); Telecanthus (Very frequent (99-80%)); Failure to thrive in infancy (Very frequent (99-80%)); Abnormal cardiovascular system morphology (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Rubinstein-Taybi 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 Rubinstein-Taybi 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.