Definition of Rubinstein-Taybi syndrome:

Rubinstein-Taybi syndrome is a genetic disease characterized by broad thumbs and toes, short stature, distinctive facial features, and varying degreess of mental retardation.

Causes, incidence, and risk factors:

Rubinstein-Taybi syndrome is a rare condition, affecting about 1 in 125,000 people. Most persons with RTS have a defect in a gene that leads to an abnormal CREB binding protein (CREBBP).

About 10% of patients, typically with more severe problems, are missing the gene entirely and do not make any CREBBP.

Most cases are sporadic and likely due to a new mutation occurring during fetal development, which was not passed on by either parent. However, in some cases, it is inherited in an autosomal dominant fashion, which means that if one parent passes on the defective gene, the child will be affected.

Symptoms:

• Broadening of the thumbs and big toes
• Constipation
• Excess hair on body (hirsutism)
• Heart defects possibly requiring surgery (about 30% of patients)
• Mental retardation
• Seizures
• Short stature that is noticeable after birth
• Slow development of cognitive skills
• Slow development of motor skills accompanied by low muscle tone

Signs and tests:

Examination and testing may reveal:

• An underdeveloped bone in the midface
• Narrow palate
• Crowded teeth
• Unsteady or stiff walking gait
• Downward-slanted eyes
• Low-set ears or malformed ears
• Drooping eyelid (ptosis)
• Cataracts
• Coloboma (a defect in the iris of the eye)
• Cryptorchidism or other testicular problems
• Macrocephaly (excessively large head) or microcephaly (excessively small head)
• Skeletal (limb) abnormalities including the last segment of the other fingers and toes, appearing broad on x-rays or physical examination
• Thick and arched eyebrows with long eyelashes
• Narrow, small, or recessed mouth with crowded teeth
• Prominent or "beaked" nose
• Absent or extra kidney, and other problems with kidney or bladder

Genetic tests can be done to determine if the CREBBP gene is missing.

Treatment:

There is no specific treatment for Rubinstein-Taybi syndrome. Symptoms such as mental retardation are treated as necessary with speech and cognitive therapy. Surgical repair of thumbs or great toes can sometimes improve grasp or relieve discomfort. Treatment may not be necessary in all cases.

Support Groups:

Rubinstein-Taybi Parents Group USA -- www.rubinstein-taybi.org

Expectations (prognosis):

The majority of children can learn to read at an elementary level. The majority have delayed motor development, but on average, they learn to walk by 2 1/2 years of age.

Complications:

Complications depend on the symptoms that are present. Feeding difficulties are common in infancy. Recurrent ear infections with hearing loss can result.

Abnormal heart structures at birth and abnormal heart rhythms have been reported.

There is an increased risk for keloid formation of the skin.

Calling your health care provider:

Call for an appointment with your health care provider if you child does not seem to be developing normally. An appointment with a geneticist is appropriate if the provider finds signs of Rubinstein-Taybi syndrome such as broad thumbs and toes.

Prevention:

Genetic counseling is advised for couples with a family history of this disease who are planning a pregnancy.