Rubinstein-Taybi Syndrome

What is Rubinstein-Taybi syndrome?

Rubinstein-Taybi syndrome is a condition characterised by short stature, moderate to severe mental retardation, distinctive facial features, and broad thumbs and first toes. Other features of the disorder vary among affected individuals. People with this condition have an increased risk of developing noncancerous and cancerous tumours, leukaemia (cancer of blood-forming tissue), and lymphoma (cancer of immune system cells).

How common is Rubinstein-Taybi syndrome?

This condition is uncommon; it occurs in an estimated 1 in 125,000 births.

What genes are related to Rubinstein-Taybi syndrome?

Mutations in the CREBBP and EP300 genes cause Rubinstein-Taybi syndrome.

Mutations in the CREBBP gene are responsible for some cases of Rubenstein-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 fetal development. If one copy of the CREBBP gene is deleted or mutated, cells make only half of the normal amount of CREB binding protein. Although a reduction in the amount of this protein disrupts normal development before and after birth, researchers have not determined how it leads to the specific 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 mutations inactivate one 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 in people with EP300 mutations are similar to those with mutations in the CREBBP gene.

More than half of people with Rubinstein-Taybi syndrome do not have an identified mutation in the CREBBP or EP300 gene. The cause of the condition is unknown in these cases; researchers believe that mutations in other genes may also be responsible for the disorder.

How do people inherit Rubinstein-Taybi 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. Most cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

What other names do people use for Rubinstein-Taybi syndrome?

• Broad Thumb-Hallux Syndrome
• RSTS
• RTS